Persian Muslim scholar Naṣīr al-Dīn al-Ṭūsī
Title	Khawaja Nasir
Born	18 February 1201 (11 Jamadi al-Ula, 597)
Died	26 June 1274(1274-06-26) (aged 73) (18 Dhu'l-Hijjah 672)
Ethnicity	Persian
Region	Iran
Maddhab	Twelver Shī‘ah
School tradition	Avicennism
Main interests	Islamic Theology, Islamic Philosophy, Astronomy, Mathematics, Chemistry, Biology and Medicine, Physics, Science
Notable ideas	Evolution, Spherical trigonometry, Tusi-couple
Works	Rawḍa-yi Taslīm, Tajrid al-'Aqaid, Akhlaq-i-Nasri, Zij-i ilkhani, al-Risalah al-Asturlabiyah, Al-Tadhkirah fi'ilm al-hay'ah
Influences	Avicenna, Fakhr al-Din al-Razi, Mo'ayyeduddin Urdi
Influenced	ibn Khaldun, Qutb al-Din al-Shirazi, Ibn al-Shatir, Copernicus

Khawaja Muḥammad ibn Muḥammad ibn Ḥasan Ṭūsī (Persian: محمد بن محمد بن الحسن طوسی‎) (born 18 February 1201 in Ṭūs, Khorasan – died on 26 June 1274 in al-Kāżimiyyah district of metropolitan Baghdad), better known as Naṣīr al-Dīn al-Ṭūsī (Persian: نصیر الدین طوسی‎‎; or simply Tusi in the West), was a Persian^[1][2][3][4] polymath and prolific writer: an astronomer, biologist, chemist, mathematician, philosopher, physician, physicist, scientist, theologian and Marja Taqleed. He was of the Ismaili-, and subsequently Twelver Shī‘ah Islamic belief.^[5] The Muslim scholar Ibn Khaldun (1332–1406) considered Tusi to be the greatest of the later Persian scholars.^[6]

Biography[link]

Nasir al-Din Tusi was born in the city of Tus in medieval Khorasan (now in north-eastern Iran) in the year 1201 and began his studies at an early age. In Hamadan and Tus he studied the Qur'an, Hadith, Shi'a jurisprudence, logic, philosophy, mathematics, medicine and astronomy.^[7]

He was apparently born into a Shī‘ah family and lost his father at a young age. Fulfilling the wish of his father, the young Muhammad took learning and scholarship very seriously and travelled far and wide to attend the lectures of renowned scholars and acquire the knowledge which guides people to the happiness of the next world. At a young age he moved to Nishapur to study philosophy under Farid al-Din Damad and mathematics under Muhammad Hasib.^[8] He met also Farid al-Din al-'Attar, the legendary Sufi master who was later killed by Mongol invaders and attended the lectures of Qutb al-Din al-Misri.

In Mosul he studied mathematics and astronomy with Kamal al-Din Yunus (d. 639/1242). Later on he corresponded with Sadr al-Din al-Qunawi, the son-in-law of Ibn al-'Arabi, and it seems that mysticism, as propagated by Sufi masters of his time, was not appealing to his mind and once the occasion was suitable, he composed his own manual of philosophical Sufism in the form of a small booklet entitled Awsaf al-Ashraf "The Attributes of the Illustrious".

As the armies of Genghis Khan swept his homeland, he was captured by the Ismailis and made his most important contributions in science during this time when he was moving from one stronghold to another. He finally joined Hulagu Khan's ranks, after the invasion of the Alamut castle by the Mongol forces.

Works[link]

Tusi has about 150 works in Persian and Arabic.^[9]

A Treatise on Astrolabe by Tusi, Isfahan 1505

• Kitāb al-Shakl al-qattāʴ Book on the complete quadrilateral. A five volume summary of trigonometry.
• Al-Tadhkirah fi'ilm al-hay'ah – A memoir on the science of astronomy. Many commentaries were written about this work called Sharh al-Tadhkirah (A Commentary on al-Tadhkirah) - Commentaries were written by Abd al-Ali ibn Muhammad ibn al-Husayn al-Birjandi and by Nazzam Nishapuri.
• Akhlaq-i-Nasri – A work on ethics.
• al-Risalah al-Asturlabiyah – A Treatise on astrolabe.
• Zij-i ilkhani (Ilkhanic Tables) – A major astronomical treatise, completed in 1272.
• sharh al-isharat (Commentary on Avicenna's Isharat)
• Awsaf al-Ashraf a short mystical-ethical work in Persian
• Tajrīd al-iʿtiqād (Summation of Belief) – A commentary on Shia doctrines.

Achievements[link]

Tusi couple from Vat. Arabic ms 319

During his stay in Nishapur, Tusi established a reputation as an exceptional scholar. "Al-Tusi’s prose writing, which number over 150 works, represent one of the largest collections by a single Islamic author. Writing in both Arabic and Persian, Nasir al-Din Tusi dealt with both religious (“Islamic”) topics and non-religious or secular subjects (“the ancient sciences”).^[9] His works include the definitive Arabic versions of the works of Euclid, Archimedes, Ptolemy, Autolycus, and Theodosius of Bithynia.^[9]

Astronomy[link]

The Astronomical Observatory of Nasir al-Din al-Tusi.

Tusi convinced Hulegu Khan to construct an observatory for establishing accurate astronomical tables for better astrological predictions. Beginning in 1259, the Rasad Khaneh observatory was constructed in Azarbaijan, west of Maragheh, the capital of the Ilkhanate Empire.

Based on the observations in this for the time being most advanced observatory, Tusi made very accurate tables of planetary movements as depicted in his book Zij-i ilkhani (Ilkhanic Tables). This book contains astronomical tables for calculating the positions of the planets and the names of the stars. His model for the planetary system is believed to be the most advanced of his time, and was used extensively until the development of the heliocentric model in the time of Nicolaus Copernicus. Between Ptolemy and Copernicus, he is considered by many to be one of the most eminent astronomers of his time, and his work and theory in astronomy can also be compared to that of the Chinese scientist Shen Kuo (1031-1095 AD)^{[citation needed]}

For his planetary models, he invented a geometrical technique called a Tusi-couple, which generates linear motion from the sum of two circular motions. He used this technique to replace Ptolemy's problematic equant^[10] for many planets, but was unable to find a solution to Mercury, which was solved later by Ibn al-Shatir as well as Ali Qushji^[11]. The Tusi couple was later employed in Ibn al-Shatir's geocentric model and Nicolaus Copernicus' heliocentric Copernican model^[12]. He also calculated the value for the annual precession of the equinoxes and contributed to the construction and usage of some astronomical instruments including the astrolabe.

Ṭūsī criticized Ptolemy's use of observational evidence to show that the Earth was at rest, noting that such proofs were not decisive. Although it doesn't mean that he was a supporter of mobility of the earth, as he and his 16th-century commentator al-Bīrjandī, maintained that the earth's immobility could be demonstrated, but only by physical principles found in natural philosophy.^[13] Tusi's criticisms of Ptolemy were similar to the arguments later used by Copernicus in 1543 to defend the Earth's rotation.^[14]

About the real essence of the Milky Way, Ṭūsī in his Tadhkira writes: "The Milky Way, i.e. the galaxy, is made up of a very large number of small, tightly-clustered stars, which, on account of their concentration and smallness, seem to be cloudy patches. because of this, it was likend to milk in color." ^[15] Three centuries later the proof of the Milky Way consisting of many stars came in 1610 when Galileo Galilei used a telescope to study the Milky Way and discovered that it is really composed of a huge number of faint stars.^[16]

Biology[link]

In his Akhlaq-i-Nasri, Al-Tusi put forward a basic theory for the evolution of species. He begins his theory of evolution with the universe once consisting of equal and similar elements. According to Tusi, internal contradictions began appearing, and as a result, some substances began developing faster and differently from other substances. He then explains how the elements evolved into minerals, then plants, then animals, and then humans. Tusi then goes on to explain how hereditary variability was an important factor for biological evolution of living things:^[17]

"The organisms that can gain the new features faster are more variable. As a result, they gain advantages over other creatures. [...] The bodies are changing as a result of the internal and external interactions."

Tusi discusses how organisms are able to adapt to their environments:^[17]

"Look at the world of animals and birds. They have all that is necessary for defense, protection and daily life, including strengths, courage and appropriate tools [organs] [...] Some of these organs are real weapons, [...] For example, horns-spear, teeth and claws-knife and needle, feet and hoofs-cudgel. The thorns and needles of some animals are similar to arrows. [...] Animals that have no other means of defense (as the gazelle and fox) protect themselves with the help of flight and cunning. [...] Some of them, for example, bees, ants and some bird species, have united in communities in order to protect themselves and help each other."

Tusi recognized three types of living things: plants, animals, and humans. He wrote:^[17]

"Animals are higher than plants, because they are able to move consciously, go after food, find and eat useful things. [...] There are many differences between the animal and plant species, [...] First of all, the animal kingdom is more complicated. Besides, reason is the most beneficial feature of animals. Owing to reason, they can learn new things and adopt new, non-inherent abilities. For example, the trained horse or hunting falcon is at a higher point of development in the animal world. The first steps of human perfection begin from here."

Tusi then explains how humans evolved from advanced animals:^[17]

"Such humans [probably anthropoid apes] live in the Western Sudan and other distant corners of the world. They are close to animals by their habits, deeds and behavior. [...] The human has features that distinguish him from other creatures, but he has other features that unite him with the animal world, vegetable kingdom or even with the inanimate bodies. [...] Before [the creation of humans], all differences between organisms were of the natural origin. The next step will be associated with spiritual perfection, will, observation and knowledge. [...] All these facts prove that the human being is placed on the middle step of the evolutionary stairway. According to his inherent nature, the human is related to the lower beings, and only with the help of his will can he reach the higher development level."

Chemistry and Physics[link]

In chemistry and physics, Tusi stated a version of the law of conservation of mass. He wrote that a body of matter is able to change, but is not able to disappear:^[17]

"A body of matter cannot disappear completely. It only changes its form, condition, composition, colour and other properties and turns into a different complex or elementary matter."

Logic[link]

Nasir al-Din al-Tusi was a supporter of Avicennian logic, and wrote the following commentary on Avicenna's theory of absolute propositions:

"What spurred him to this was that in the assertoric syllogistic Aristotle and others sometimes used contradictories of absolute propositions on the assumption that they are absolute; and that was why so many decided that absolutes did contradict absolutes. When Avicenna had shown this to be wrong, he wanted to give a way of construing those examples from Aristotle."^[18]

Mathematics[link]

Al-Tusi was the first to write a work on trigonometry independently of astronomy.^[19] Al-Tusi, in his Treatise on the Quadrilateral, gave an extensive exposition of spherical trigonometry, distinct from astronomy.^[20] It was in the works of Al-Tusi that trigonometry achieved the status of an independent branch of pure mathematics distinct from astronomy, to which it had been linked for so long.^[21][22]

He was the first to list the six distinct cases of a right triangle in spherical trigonometry.

This followed earlier work by Greek mathematicians such as Menelaus of Alexandria, who wrote a book on spherical trigonometry called Sphaerica, and the earlier Muslim mathematicians Abū al-Wafā' al-Būzjānī and Al-Jayyani.

In his On the Sector Figure, appears the famous law of sines for plane triangles.^[23]

Failed to parse (Missing texvc executable; please see math/README to configure.): \frac{a}{\sin A} = \frac{b}{\sin B} = \frac{c}{\sin C}

He also stated the law of sines for spherical triangles,^[24][25] discovered the law of tangents for spherical triangles, and provided proofs for these laws.^[23]

In 1265, Tusi wrote a manuscript regarding the calculation for nth roots of an integer^{[citation needed]}. Moreover, he revealed the coefficients of the expansion of a binomial to any power giving the binomial formula and the Pascal triangle relations between binomial coefficients^{[citation needed]}. He also wrote a famous work on theory of colour, based on mixtures of black and white, and included sections on jewels and perfumes^{[citation needed]}.

Influence and legacy[link]

1956 Iranian stamp for the 700th anniversary of his death.

A 60-km diameter lunar crater located on the southern hemisphere of the moon is named after him as "Nasireddin". A minor planet 10269 Tusi discovered by Soviet astronomer Nikolai Stepanovich Chernykh in 1979 is named after him.^[26][27] The K. N. Toosi University of Technology in Iran and Observatory of Shamakhy in the Republic of Azerbaijan are also named after him.

See also[link]

• Persian science
• Islamic Golden Age
• Islamic science
• Islamic scholars
• List of Muslim scholars
• List of Shi'a Muslims
• List of Iranian scientists
• Shen Kuo

References[link]

Further reading[link]

• "Ṭūsī, Muḥammad Ibn Muḥammad Ibn al-Ḥasan al-". Dictionary of Scientific Biography. New York: Charles Scribner's Sons. 1970–80. ISBN 0684101149. 
• O'Connor, John J.; Robertson, Edmund F., "Nasir al-Din al-Tusi", MacTutor History of Mathematics archive, University of St Andrews, http://www-history.mcs.st-andrews.ac.uk/Biographies/Al-Tusi_Nasir.html .
• Encyclopædia Iranica, "AḴLĀQ-E NĀṢERĪ", G.M. Wickens [4]
• Encyclopædia Iranica, "AWṢĀF AL-AŠRĀF", G.M. Wickens [5]
• Encyclopædia Iranica, "Nasir al-Din al-Tusi" George Saliba [6]

External links[link]

• Ragep, F. Jamil (2007). "Ṭūsī: Abū Jaʿfar Muḥammad ibn Muḥammad ibn al‐Ḥasan Naṣīr al‐Dīn al‐Ṭūsī". In Thomas Hockey et al. The Biographical Encyclopedia of Astronomers. New York: Springer. pp. 1153–5. ISBN 978-0-387-31022-0. http://islamsci.mcgill.ca/RASI/BEA/Tusi_BEA.htm.  (PDF version)
• Nasr, Seyyed Hossein (2008) [1970-80]. "Al-Ṭūsī, Muḥammad Ibn Muḥammad Ibn Al-Ḥasan Usually Known as Naṣir Al-Dīn". Complete Dictionary of Scientific Biography. Encyclopedia.com. http://www.encyclopedia.com/doc/1G2-2830904400.html. 
• Biography by Islamic Insights
• Biography by Islamic Philosophy Online
• Biography by The Internet Encyclopedia of Philosophy
• Kerry Magruder, History of Science Online: Islamic and Early Medieval Science, University of Oklahoma
• Islam Online.
• http://www.famousmuslims.com/NASIR%20AL-DIN%20AL-TUSI.htm
• http://www.britannica.com/eb/article-9073899
• The Rekhaganita. An 18th century Sanskrit translation of Nasir al-Din al-Tusi's recension of Euclid's Elements.
• Richard Covington, Rediscovering Arabic Science, 2007, Saudi Aramco World

Nicolaus Copernicus
Portrait, 1580, Toruń Old Town City Hall
Born	(1473-02-19)19 February 1473 Thorn (Toruń), Royal Prussia, Kingdom of Poland
Died	24 May 1543(1543-05-24) (aged 70) Frauenburg (Frombork), Prince-Bishopric of Warmia, Royal Prussia, Kingdom of Poland
Fields	Mathematics, astronomy, canon law, medicine, economics
Alma mater	Kraków University, Bologna University, University of Padua, University of Ferrara
Known for	Heliocentrism, Copernicus' Law
Signature

Nicolaus Copernicus (German: Nikolaus Kopernikus; Italian: Nicolò Copernico; Polish:  Mikołaj Kopernik (help·info); in his youth, Niclas Koppernigk;^[1] 19 February 1473 – 24 May 1543) was a Renaissance astronomer and the first person to formulate a comprehensive heliocentric cosmology which displaced the Earth from the center of the universe.^[2]

Copernicus' epochal book, De revolutionibus orbium coelestium (On the Revolutions of the Celestial Spheres), published just before his death in 1543, is often regarded as the starting point of modern astronomy and the defining epiphany that began the scientific revolution. His heliocentric model, with the Sun at the center of the universe, demonstrated that the observed motions of celestial objects can be explained without putting Earth at rest in the center of the universe. His work stimulated further scientific investigations, becoming a landmark in the history of science that is often referred to as the Copernican Revolution.

Among the great polymaths of the Renaissance, Copernicus was a mathematician, astronomer, jurist with a doctorate in law, physician, quadrilingual polyglot, classics scholar, translator, artist,^[3] Catholic cleric, governor, diplomat and economist.

Life[link]

Thorn birthplace (ul. Kopernika 15, left). Together with the house at no. 17 (right), it forms the Muzeum Mikołaja Kopernika.

Nicolaus Copernicus was born on 19 February 1473 in the city of Thorn, in the province of Royal Prussia, in the Crown of the Kingdom of Poland.^[4][5]

His father was a merchant from Kraków and his mother was the daughter of a wealthy Thorn merchant. Nicolaus was the youngest of four children. His brother Andreas (Andrew) became an Augustinian canon at Frauenburg (Frombork). His sister Barbara, named after her mother, became a Benedictine nun and, in her final years (she died after 1517), prioress of a convent in Culm (Kulm) (Chełmno). His sister Katharina married the businessman and Thorn city councilor Barthel Gertner and left five children, whom Copernicus looked after to the end of his life.^[6]

Copernicus never married or had children.

"Towards the close of 1542, he was seized with apoplexy and paralysis." He died on 24 May 1543, on the day that he was presented with an advance copy of his De revolutionibus orbium coelestium.^[7]

Father's family[link]

The father’s family can be traced to a village in Silesia near Neiße (Nysa). The village's name has been variously spelled Kopernik,^[8] Köppernig, Köppernick, and today Koperniki. In the 14th century, members of the family began moving to various other Silesian cities, to the Polish capital, Kraków (Cracow, 1367), and to Thorn (1400). The father, likely the son of Jan, came from the Kraków line.^[9]

Nicolaus was named after his father, who appears in records for the first time as a well-to-do merchant who dealt in copper, selling it mostly in Danzig (Gdańsk).^[10][11] He moved from Kraków to Thorn around 1458.^[12] Thorn, situated on the Vistula River, was at that time embroiled in the Thirteen Years' War (1454–66), in which the Kingdom of Poland and the Prussian Confederation, an alliance of Prussian cities, gentry and clergy, fought the Teutonic Order over control of the region. In this war Hanseatic cities like Danzig and Thorn, the hometown of Nicolaus Copernicus, chose to support the Polish king, who promised to respect the cities' traditional vast independence, which the Teutonic Order had challenged. The father of Nicolaus was actively engaged in the politics of the day, and supported Poland and the cities against the Teutonic Order.^[13] In 1454 he mediated negotiations between Poland’s Cardinal Zbigniew Oleśnicki and the Prussian cities for repayment of war loans. In the Second Peace of Thorn (1466), the Teutonic Order formally relinquished all claims to its western provinces, which as Royal Prussia remained a region of Poland for the next 300 years.

The father married Barbara Watzenrode, the astronomer's mother, between 1461 and 1464. He died sometime between 1483 and 1485. Upon the father’s death, young Nicolaus’ maternal uncle, Lucas Watzenrode the Younger (1447–1512), took the boy under his protection and saw to his education and career.

Mother's family[link]

Copernicus' maternal uncle, Lucas Watzenrode the Younger

Nicolaus’ mother, Barbara Watzenrode, was the daughter of Lucas Watzenrode the Elder and his wife Katherine (née Modlibóg).^[14][15][16] Not much is known about her life, but she is believed to have died when Nicolaus was a small boy. The Watzenrodes had come from the Schweidnitz (Świdnica) region of Silesia and had settled in Thorn after 1360, becoming prominent members of the city’s patrician class.^[17] Through the Watzenrodes' extensive family relationships by marriage, they were related to wealthy families of Thorn, Danzig and Elbing (Elbląg), and to the prominent Czapski, Działyński, Konopacki and Kościelecki noble families.^[18] The Modlibógs (literally, in Polish, "Pray to God") were a prominent Roman Catholic Polish family who had been well known in Poland's history since 1271.^[16] Lucas and Katherine had three children: Lucas Watzenrode the Younger, who would become Copernicus' patron; Barbara, the astronomer's mother; and Christina, who in 1459 married the merchant and mayor of Thorn, Tiedeman von Allen.

Lucas Watzenrode the Elder was well regarded in Thorn as a devout man and honest merchant, and he was active politically. He was a decided opponent of the Teutonic Knights and an ally of Polish King Casimir IV Jagiellon.^[19] In 1453 he was the delegate from Thorn at the Graudenz (Grudziądz) conference that planned to ally the cities of the Prussian Confederation with Casimir IV in their subsequent war against the Teutonic Knights.^[6] During the Thirteen Years' War that ensued the following year, he actively supported the war effort with substantial monetary subsidies, with political activity in Thorn and Danzig, and by personally fighting in battles at Lessen (Łasin) and Marienburg (Malbork).^[20] He died in 1462.

Lucas Watzenrode the Younger, the astronomer's maternal uncle and patron, was educated at the University of Krakow (now Jagiellonian University) and at the universities of Cologne and Bologna. He was a bitter opponent of the Teutonic Order^[21][22] and its Grand Master, who once referred to Watzenrode as “the devil incarnate.”^[23] In 1489 Watzenrode was elected Bishop of Warmia (Ermeland, Ermland) against the preference of King Casimir IV, who had hoped to install his own son in that seat. As a result, Watzenrode quarreled with the king until Casimir IV’s death three years later.^[24] Watzenrode was then able to form close relations with three successive Polish monarchs: John I Albert, Alexander Jagiellon, and Sigismund I the Old. He was a friend and key advisor to each ruler, and his influence greatly strengthened the ties between Warmia and Poland proper.^[25][26] Watzenrode came to be considered the most powerful man in Warmia, and his wealth, connections and influence allowed him to secure Copernicus’ education and career as a canon at Frombork Cathedral.

Languages[link]

German-language letter from Copernicus to Duke Albert of Prussia, giving medical advice for George von Kunheim (1541)

Copernicus is postulated to have spoken Latin, German, and Polish with equal fluency. He also spoke Greek and Italian.^{[27][28][29][30]} The vast majority of Copernicus’ surviving works are in Latin, which in his lifetime was the language of academia in Europe. Latin was also the official language of the Roman Catholic Church and of Poland's royal court, and thus all of Copernicus’ correspondence with the Church and with Polish leaders was in Latin.

There survive a few documents written by Copernicus in German. Martin Carrier mentions this as a reason to consider Copernicus’ native language to have been German.^[31] Other arguments are that Copernicus was born in a predominantly German-speaking town and that, while studying law at Bologna in 1496, he signed into the German natio (Natio Germanorum)—a student organization which, according to its 1497 by-laws, was open to students of all kingdoms and states whose mother-tongue ("Muttersprache") was German.^[32] However, according to French philosopher Alexandre Koyre, this in itself does not imply that Copernicus considered himself German, since students from Prussia and Silesia were routinely placed in that category, which carried certain privileges that made it a natural choice for German-speaking students, regardless of their ethnicity or self-identification.^{[32][33][34][35][36][37]}

Name[link]

In Copernicus’ day, people were often called after the places where they lived. Like the Silesian village that inspired it, Copernicus’ surname has been spelled variously. Today the English-speaking world knows the astronomer principally by the Latinized name, "Nicolaus Copernicus."

The surname likely had something to do with the local Silesian copper-mining industry,^[38] though some scholars assert that it may have been inspired by the dill plant (in Polish, "koperek" or "kopernik") that grows wild in Silesia.^[39]

As was to be the case with William Shakespeare a century later,^[40] numerous spelling variants of the name are documented for the astronomer and his relatives. The name first appeared as a place name in Silesia in the 13th century, where it was spelled variously in Latin documents. Copernicus "was rather indifferent about orthography."^[41] During his childhood, the name of his father (and thus of the future astronomer) was recorded in Thorn as Niclas Koppernigk around 1480.^[42][43] At Kraków he signed his name "Nicolaus Nicolai de Torunia."^[15] At Bologna in 1496, he registered in the Matricula Nobilissimi Germanorum Collegii resp. Annales Clarissimae Nacionis Germanorum of the Natio Germanica Bononiae as Dominus Nicolaus Kopperlingk de Thorn – IX grosseti.^[44][45] At Padua, Copernicus signed his name "Nicolaus Copernik", later as "Coppernicus."^[41] He signed a self-portrait, a copy of which is now at Jagiellonian University, "N Copernic."^[46] The astronomer Latinized his name to Coppernicus, generally with two "p"s (in 23 of 31 documents studied),^[47] but later in life he used a single "p". On the title page of De revolutionibus, Rheticus published the name as (in the genitive, or possessive, case) "Nicolai Copernici".

Education[link]

Collegium Maius, Kraków

Nicolaus Copernicus Monument in Kraków

Copernicus' uncle Watzenrode maintained contacts with the leading intellectual figures in Poland and was a friend of the influential Italian-born humanist and Kraków courtier, Filippo Buonaccorsi.^[48] Watzenrode seems first to have sent young Copernicus to the St. John's School at Thorn where he himself had been a master. Later, according to Armitage (some scholars differ), the boy attended the Cathedral School at Leslau, up the Vistula River from Thorn, which prepared pupils for entrance to the University of Krakow, Watzenrode's alma mater in Poland's capital.^[49]

In the winter semester of 1491–92 Copernicus, as "Nicolaus Nicolai de Thuronia," matriculated together with his brother Andrew at the University of Krakow (now Jagiellonian University). Copernicus began his studies in the Department of Arts (from the fall of 1491, presumably until the summer or fall of 1495) in the heyday of the Kraków astronomical-mathematical school, acquiring the foundations for his subsequent mathematical achievements. According to a later but credible tradition (Jan Brożek), Copernicus was a pupil of Albert Brudzewski, who by then (from 1491) was a professor of Aristotelian philosophy but taught astronomy privately outside the university; Copernicus became familiar with Brożek's widely read commentary to Georg von Peuerbach's Theoricæ novæ planetarum and almost certainly attended the lectures of Bernard of Biskupie and Wojciech Krypa of Szamotuły and probably other astronomical lectures by Jan of Głogów, Michael of Wrocław, Wojciech of Pniewy and Marcin Bylica of Olkusz.^[50]

Copernicus' Kraków studies gave him a thorough grounding in the mathematical-astronomical knowledge taught at the university (arithmetic, geometry, geometric optics, cosmography, theoretical and computational astronomy), a good knowledge of the philosophical and natural-science writings of Aristotle (De coelo, Metaphysics) and Averroes (which later would play an important role in shaping his theory), stimulated his interest in learning, and made him conversant with humanistic culture. Copernicus broadened the knowledge that he took from the university lecture halls with independent reading of books that he acquired during his Kraków years (Euclid, Haly Abenragel, the Alfonsine Tables, Johannes Regiomontanus' Tabulae directionum); to this period, probably, also date his earliest scientific notes, now preserved partly at Uppsala University.^[51] At Kraków Copernicus began collecting a large library on astronomy; it would later be carried off as war booty by the Swedes during the Deluge and is now at the Uppsala University Library.

Copernicus' four years at Kraków played an important role in the development of his critical faculties and initiated his analysis of the logical contradictions in the two most polular systems of astronomy—Aristotle's theory of homocentric spheres, and Ptolemy's mechanism of eccentrics and epicycles—the surmounting and discarding of which constituted the first step toward the creation of Copernicus' own doctrine of the structure of the universe.^[51]

Without taking a degree, probably in the fall of 1495, Copernicus left Kraków for the court of his uncle Watzenrode, who in 1489 had been elevated to Prince-Bishop of Warmia and soon (after November 1495) sought to place his nephew in a Warmia canonry vacated by 26 August 1495 death of its previous tenant. For unclear reasons—probably due to opposition from part of the chapter, who appealed to Rome—Copernicus' installation was delayed, inclining Watzenrode to send both his nephews to study law in Italy, seemingly with a view to furthering their ecclesiastic careers and thereby also strengthening his own influence in the Warmia chapter.^[51]

Leaving Warmia in mid-1496—possibly with the retinue of the chapter's chancellor, Jerzy Pranghe, who was going to Italy—in the fall (October?) of that year Copernicus arrived in Bologna and a few months later (after 6 January 1497) signed himself into the register of the Bologna University of Jurists' "German nation," which also included Polish youths from Silesia, Prussia and Pomerania as well as students of other nationalities.^[51]

It was only on 20 October 1497 that Copernicus, by proxy, formally succeeded to the Warmia canonry, which had been granted to him two years earlier. To this, by a document dated 10 January 1503 at Padua, he would add a sinecure at the Collegiate Church of the Holy Cross in Breslau (Wrocław), Silesia, Bohemia. Despite having received a papal indult on 29 November 1508 to receive further benefices, through his ecclesiastic career Copernicus not only did not acquire further prebends and higher stations (prelacies) at the chapter, but in 1538 he relinquished the Breslau sinecure. It is uncertain whether he was ordained a priest; he may only have taken minor orders, which sufficed for assuming a chapter canonry.^[51]