"We now reach Plato's final argument against the identification of knowledge with perception. He begins by pointing out that we perceive through eyes and ears, rather than with them, and he goes on to point out that some of our knowledge is not connected with any sense organ. We can know, for instance, that sounds and colors are unlike, though no organ of sense can perceive both. There is no special organ for "existence and non-existence, likeness and unlikeness, sameness and differences, and also unity and numbers in general." The same applies to honorable and dishonorable, and good and bad. "The mind contemplates some things through it own instrumentality, others through the bodily faculties." We perceive hard and soft through touch, but it is the mind that judges that they exist and that they are contraries. Only the mind can reach existence, and we cannot reach truth if we do not reach existence. It follows that we cannot know things through the senses alone, since through the senses alone we cannot know that things exist. Therefore knowledge consists in reflection, not in impressions, and perception is not knowledge, because it "has no part in apprehending the truth, since it has none in apprehending existence.""