[Knowledge] and sense-perception, while belonging to different kinds, are not too far apart; they differ from each other in genus. For conceptualization is the genus of knowledge, but sense-perception is not conceptualization.[1] However, they are identical by analogy. For, as sense-perception is to the sense-perceptible things, so too knowledge is to the knowable things, and both of them have critical nature; at any rate some people already said that knowledge as well as sense-perception are the same thing because of their resemblance. But they differ from each other: for sense-perception is related to those things which can be otherwise, but knowledge does not take part in what can be otherwise. And knowledge is cognizant of the substance of each of the knowledgeable things, but sense-perception is not cognizant of the substance of any sensible things. And whereas knowledge is acquired in addition, sense-perception is acquired from the very beginning. And sense-perception is common to other living beings, but knowledge is peculiar to human beings or generally to rational beings.[2] Sense-perception is acquired by nature, knowledge by teaching. And in the case of sense-perception, the dispositional state promotes the activities (energeiai); for we see when we are able to see; but in the case of knowledge, we acquire such dispositional states through the activities (energeiai). For, engaging with letters (grammata), we become grammarians (grammatikoi). And if the sense-perception is destroyed, the living being is destroyed with it as well. But if the knowledge is destroyed, the living being is not destroyed.[3]