"Hight Dioscorides; and Orpheus saw I, Tully and Livy, and moral Seneca, Euclid, geometrician, and Ptolemy, Galen, Hippocrates, and Avicenna, Averroes, who the great Comment made."

(Canto 4, lines 140-144)

Dioscorides (1st century AD) was a famous Greek physician and natural historian, remembered for his monumental work on herbal medicine "De Materia Medica".

Orpheus is a poet and musician from Greek mythology, whose beautiful singing according to legend had the power to tame wild beasts, stop rivers from flowing and move insentient stones.

Tully is another of Cicero's names (full name Marcus Tullius Cicero, 106-43 BC), included here because of his accomplishments in philosophy.

Livy (full name Titus Livius Patavinus, 59 BC - 17 AD), was a historian, remembered for his work on Rome and the Romans.

Seneca (full name Lucius Annaeus Seneca, 4 BC - 65 AD) was a famous Roman orator, philosopher and poet. He was a tutor of the tyrant Nero, but was forced to commit suicide after he was suspected to conspire against him. In life he was an adherent of Stoic philosophy and the author of nine tragedies.

Euclid (fl. 300 BC) is remembered as the greatest of the Greek mathematicians, famous for his axioms on geometry.

Ptolemy (ca. 90-178) was a Greek mathematician, phycisist and astronomer. The Geocentric theory of the universe, commonly accepted during the Middle Ages until the Copernican revolution of the 16th century, is often associated with him.

Galen (129-201) was a famous Greek physician. He pioneered the observational method of dissection and vivisection as the basis of scientific medicine. His influence on the science of medicine lasted for over one millennium.

Hippocrates (ca. 460-370), ancient Greek physician, often referred to as the Father of Medicine. A corpus of texts including the "Aphorisms", "Epidemics" and "On Ancient Medicine" are associated with him.

Avicenna (Abū ʿAlī al-Ḥusayn ibn ʿAbd Allāh ibn Sīnā, c. 980-1037) was an Persian phycisian and philosopher, among others, regarded as a towering figure of the Islamic Golden Age. He is the author of commentaries on works by Aristotle and Neoplatonic philosophers, which had a considerable influence on 13th century thought. In the field of medicine, his most famous works are "The Book of Healing" and "The Canon of Medicine".

Finally, Averroes (Abū ʿAlī al-Ḥusayn ibn ʿAbd Allāh ibn Sīnā, 1126-1198) was another Muslim polymath, author of key works on Aristotelian philosophy and considered an outstanding commentator on Aristotle and the Peripatetic philosophers. His theories were noticed under emperor Frederick II, became widespread in Italy and had a lasting influence on Western thought. He is also remembered for his attempts to reconcile Aristotelian philosophy with Islam.