I. Wherein is the Criterion for the Apprehension of the Soul

All things that exist are either known by sense⁴⁴² or apprehended by thought.⁴⁴³ And what falls under sense has its adequate demonstration in sense itself; for at once, with the application, it creates in us the impression⁴⁴⁴ of what underlies it. But what is apprehended by thought is known not by itself, but by its operations.⁴⁴⁵ The soul, consequently, being unknown by itself, shall be known property by its effects.