Chapter 9
Moreover, if there be the definition of a habit, take notice of what possesses it, but if the definition be of what possesses, consider the habit, and in like manner with regard to other things of this kind; e. g. if the pleasant is what is beneficial, he also who is pleased is benefited. In a word, it happens after a certain manner in such definitions, that the definer defines more things than one, since he who defines science, after a certain way defines ignorance also, likewise the scientific and the unscientific, also to know and to be ignorant, for the first being evident, the rest also in some way become evident. We must examine then, in all such cases, lest any thing should be discordant, employing the elements which are from contraries, and conjugates.
Examine too, in relatives, whether to what genus is referred, to that a certain species is referred, for instance, if apprehension to the object of apprehension, a certain apprehension also (is referred) to a certain object of apprehension, and if the multiple is to the sub-multiple, whether a certain multiple is to a certain sub-multiple, since if there is not such reference, there has been evidently an error.
Again, observe whether there is an opposite definition of the opposite, as whether the definition of the half is opposite to that of the double, since if the double be that which surpasses in the equal, the half will be what is surpassed in the equal. Likewise, also, in the case of contraries, for the definition of the contrary will be contrary according to one certain connexion of contraries, thus, if that is beneficial which is productive of good, what is productive of evil or is corruptive of good is injurious, since one of these must necessarily be contrary to that mentioned at first. If then neither be contrary to that mentioned at first, it is clear that neither of the definitions afterwards given,
