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- Ambrose, Saint, Bishop of Milan, d. 3974
- Anaximenes, of Lampsacus1
- Anderson, Thomas McArthur, 1836-19173
- Andrea da Pistoia1
- Angela, of Foligno, 1248?-13091
- Angeli, Alessandro degli2
- Angelus, Johannes, 1463-15121
- Anonymous1
- Ansari, Zakariya ibn Muhammad, ca. 1423-ca. 15201
- Anselm, Saint, Archbishop of Canterbury, 1033-11091
- Antelmi, Bonifazio1
- Antoninus, Saint, Archbishop of Florence, 1389-14593
- Appel, Nathan B.1
- Aquila, Romanus1
- Arbuthnot, Marriot, 1711-17941
- Ariosti, Attilio Malachia, 1666-17291
- Aristotle5
- Aristotle, pseud.1
- Arnaldus, de Villanova, d. 13112