- In his Encyclical of August 4, 1879, which directed the clergy to take the teachings of Aquinas as the basis of their theological position.
- The best modern edition of the works of Aquinas is that prepared at the expense of Leo XIII.
- C. O'Neill, New Things and Old in St Thomas Aquinas (1909), with biography.
- Further, while the genius of Aquinas was constructive, that of Duns Scotus was destructive; Aquinas was a philosopher, Duns a critic. The latter has been said to stand to the former in the relation of Kant to Leibnitz.
- But, as Ueberweg points out, it might fairly be urged by Aquinas that he does not pretend to explain how the individual is actually created, but merely states what he finds to be an invariable condition of the existence of individuals.