§ 345. Thus Aristotle's four heads of predicables may be split up, if we please, into nine-- 1. Definition \ > [Greek: òrismós]. 2. Synonym / 3. Designation \ | 4. Description > [Greek: îdion]. | 5. Peculiar Property/ 6. Genus \ | 7. Difference > [Greek: génos]. | 8. Generic Property/ 9. Accident--[Greek: sumbebekós]. § 346. We now pass on to the two subjects of Definition and Division, the discussion of which will complete our treatment of the second part of logic. Definition and division correspond respectively to the two kinds of quantity possessed by terms. Definition is unfolding the quantity of a term in intension. Division is unfolding the quantity of a term in extension. CHAPTER VII. _Of Definition._ § 347. To define a term is to unfold its intension, i.e. to explain its meaning. § 348. From this it follows that any term which possesses no intension cannot be defined. § 349. Hence proper names do not admit of definition, except just in so far as they do possess some slight degree of intension: Thus we can define the term 'John' only so far as to say that 'John' is the name of a male person. This is said with regard to the original intension of proper names; their acquired intension will be considered later. § 350. Again, since definition is unfolding the intension of a term, it follows that those terms will not admit of being defined whose intension is already so simple that it cannot be unfolded further. Of this nature are names of simple attributes, such as greenness, sweetness, pleasure, existence. We know what these things are, but we cannot define them. To a man who has never enjoyed sight, no language can convey an idea of the greenness of the grass or the blueness of the sky; and if a person were unaware of the meaning of the term 'sweetness,' no form of words could convey to him an idea of it. We might put a lump of sugar into his mouth, but that would not be a logical definition. § 351. Thus we see that, for a thing to admit of definition, the idea of it must be complex. Simple ideas baffle definition, but at the same time do not require it. In defining we lay out the simpler ideas which are combined in our notion of something, and so explain that complex notion. We have defined 'triangle,' when we analyse it into 'figure' and 'contained by three lines.' Similarly we have defined 'substance' when we analyse it into 'thing' and 'which can be conceived to exist by itself.'