Aristotle and Plato
stand to the left and right; Averroes lies beneath the circle that
inscribes the saint. Ranged above him, left to right, are SS. Luke and
Matthew with their attributes, two other saints (other Doctors of the
Church?), and SS. John and Mark with their attributes.
The volume of scripture standing on Thomas's lap is open to Proverbs 8:7, Veritatem meditabitur guttur meum et labia mea detestabuntur impium, "my mouth will meditate on truth, and my lips will detest the impious man" (enlargement)
More of St. Thomas Aquinas