Thomas Aquinas

Lived

1225–1274

Era

Medieval

Where

Naples, Paris and Cologne

Tradition

Roman Catholic

The Summa Theologiae

An Italian nobleman's son whose family imprisoned him for a year to stop him joining the Dominicans, and who became the most systematic thinker of the middle ages, teaching at Paris and Naples.

Why it matters

His achievement was to take Aristotle, newly available in Latin through Arabic and Syriac transmission and widely suspected of being incompatible with Christianity, and show that reason and revelation are not rivals — grace perfects nature rather than replacing it. The Summa was intended as a textbook for beginners. He stopped writing months before he died, after an experience he would only describe by saying that everything he had written seemed like straw.

All the figures, from the apostolic age to the present, or the timeline they stand in.