Justin Martyr: The Hortatory Address to the Greeks - Chapter VII.—Inconsistencies of Plato’s Doctrine.
But in these things they are convicted of thinking in contradiction to each other. And if any one will accurately criticise their writings, they have chosen to abide in harmony not even with their own opinions. Plato, at any rate, at one time says that there are three first principles of the universe—God, and matter, and form; but at another time four, for he adds the universal soul. And again, when he has already said that matter is eternal, he afterwards says that it is produced; and when he has first given to form its peculiar rank as a first principle, and has asserted for its self-subsistence, he afterwards says that this same thing is among the things perceived by the understanding. Moreover, having first declared that everything that is made is mortal he afterwards states that some of the things that are made are indestructible and immortal. What, then, is the cause why those who have been esteemed wise among you disagree not only with one another but also with themselves? Manifestly, their unwillingness to learn from those who know, and their desire to attain accurate knowledge of things heavenly by their own human excess of wisdom though they were able to understand not even earthly matters. Certainly some of your philosophers say that the human soul is in us; others, that it is around us. For not even in this did they choose to agree with one another, but, distributing, as it were, ignorance in various ways among themselves, they thought fit to wrangle and dispute with one another even about the soul. For some of them say that the soul is fire, and some that it is the air; and others, the mind; and others, motion; and others, an exhalation; and certain others say that it is a power flowing from the stars; and others, number capable of motion; and others, a generating water. And a wholly confused and inharmonious opinion has prevailed among them, which only in this one respect appears praiseworthy to those who can form a right judgment, that they have been anxious to convict one another of error and falsehood.