The italian Saint Thomas Aquinas, O.P. (also Thomas of Aquin or Aquino, c. 1225 1274). Portrait engraving by Maffeis, 1837, Italy. TOMMASO D'AQUINO was an Italian Catholic priest in the Dominican Order, a philosopher and theologian in the scholastic tradition. He was the foremost classical proponent of natural theology and the father of the Thomistic school of philosophy and theology