 The sense perceives only the outward appearance of things, and does not attain understanding (I am for the moment applying the word “sense” to the eye). It is the mind that receives images from the sense, and considers them. If the sense was deceived, so is the mind; but if not, what follows next? The mind regards only the images of things, which the eye has taken in; it studies them from this side and from that, and turns them about, putting the questions “What is this?” and “Whence comes its nature?” and “Why”—and no more than this, for it too sees nothing that is certain. (TNK: 236)