Nicene and Post Nicene-Fathers, Vol. I:
The Confessions: Book IV

p. 68

Book IV.

————————————

Then follows a period of nine years from the nineteenth year of his age, during which having lost a friend, he followed the Manichæans—and wrote books on the fair and fit, and published a work on the liberal arts, and the categories of Aristotle.

————————————