The Blessed Pope Innocent V (c. 1225 – 22 June 1276), born Pierre de Tarentaise, was Pope from 21 January 1276 until his death.

He was born around 1225 near Moûtiers in the Tarentaise region of the County of Savoy, then part of the Kingdom of Arles in the Holy Roman Empire, but now in southeastern France. In early life, he joined the Dominican Order, in which he acquired great fame as a preacher. At the papal conclave of January 1276 he became the first member of that order to become Pope. The only noteworthy feature of his brief and uneventful pontificate was the practical form assumed by his desire for reunion with the Eastern Church. He was proceeding to send legates to Michael VIII Palaeologus, the Byzantine emperor, in connection with the recent decisions of the Second Council of Lyons, when he died at Rome. Pope Innocent V was the author of several works of philosophy, theology, and canon law, including commentaries on the Pauline epistles and on the Sentences of Peter Lombard. He is sometimes referred to as famosissimus doctor.

Pope Innocent III (1160 or 1161 – 16 July 1216) was Pope from 8 January 1198 until his death. His birth name was Lotario dei Conti di Segni, sometimes anglicised to Lothar of Segni.

Pope Innocent was one of the most powerful and influential popes in the history of the papacy. He exerted a wide influence over the Christian regimes of Europe, claiming supremacy over all of Europe's kings. Pope Innocent was central in supporting the Catholic Church's reforms of ecclesiastical affairs through his decretals and the Fourth Lateran Council. This resulted in a considerable refinement of the Western canon law. Pope Innocent is notable for using interdict and other censures to compel princes to obey his decisions, although these measures were not uniformly successful. The pope called for crusades against militant heretics like the Cathars as well as Muslims. One of Pope Innocent's most critical decisions was calling upon Christian forces to begin the Fourth Crusade. Although the Crusades were, in part, originally intended to support the Byzantine Empire at Constantinople from attack by Turkish invaders, the Fourth Crusade resulted in the sack of Constantinople by the Crusaders in 1204, which greatly upset Pope Innocent.

Pope Innocent X (6 May 1574 – 7 January 1655), born Giovanni Battista Pamphilj (or Pamphili), was Pope from 1644 to 1655. Born in Rome of a family from Gubbio in Umbria who had come to Rome during the pontificate of Pope Innocent IX, he graduated from the Collegio Romano and followed a conventional cursus honorum, following his uncle Girolamo Pamphilj as auditor of the Rota, and like him, attaining the dignity of Cardinal-Priest of Sant'Eusebio, in 1629. Trained as a lawyer, he succeeded Pope Urban VIII (1623–44) on 15 September 1644, as one of the most politically shrewd pontiffs of the era, who much increased the temporal power of the Holy See. He was a great-great-great-grandson of Pope Alexander VI.

Pope Gregory XV (1621–23) sent him as nuncio to the court of the Kingdom of Naples. Urban VIII sent him to accompany his nephew, Francesco Barberini, whom he had accredited as nuncio, first in France and then in Spain, where Pamphilj had the first-hand opportunities to form an intense animosity towards the Barberini. In reward for his labors, Giovanni Battista was made apostolic nuncio at the court of Philip IV of Spain (1621–65). The position led to a life-long association with the Spaniards which was of great use during the Papal Conclave of 1644.

Francis Bacon, 1st Viscount St Alban(s),KC (22 January 1561 – 9 April 1626) was an English philosopher, statesman, scientist, jurist and author. He served both as Attorney General and Lord Chancellor of England. Although his political career ended in disgrace, he remained extremely influential through his works, especially as philosophical advocate and practitioner of the scientific method during the scientific revolution.

Bacon has been called the creator of empiricism. His works established and popularised inductive methodologies for scientific inquiry, often called the Baconian method, or simply the scientific method. His demand for a planned procedure of investigating all things natural marked a new turn in the rhetorical and theoretical framework for science, much of which still surrounds conceptions of proper methodology today.

Bacon was knighted in 1603, and created both the Baron Verulam in 1618, and the Viscount St Alban in 1621; as he died without heirs both peerages became extinct upon his death. He famously died by contracting pneumonia while studying the effects of freezing on the preservation of meat.

Pope Innocent IV (c. 1195 – 7 December 1254), born Sinibaldo Fieschi, was Pope from 25 June 1243 until his death in 1254.

Born in Genoa (although some sources say Manarola) in an unknown year, Sinibaldo was the son of Brumisan di Grillo and Ugo Fieschi, Count of Lavagna. The Fieschi were a noble merchant family of Liguria. Sinibaldo received his education at the universities of Parma and Bologna and, for a time, taught canon law at Bologna. He was considered one of the best canonists of his time and was called to serve the Pope in the Roman Curia in the year 1226.

Before his elevation to the papacy, Sinibaldo was Vice-Chancellor of the Holy Roman Church (1226–27), being created Cardinal Priest of San Lorenzo in Lucina on 18 September 1227 by Pope Gregory IX, later serving as governor of the March of Ancona from 1235 until 1240.

It is widely repeated from the 17th century on that he became bishop of Albenga in 1235, but there is no foundation to this claim.

Innocent's immediate predecessor was Pope Celestine IV, elected 25 October 1241, whose reign lasted a mere fifteen days. The events of Innocent IV's pontificate are therefore inextricably linked to the policies dominating the reigns of popes Innocent III, Honorius III and Gregory IX.