consist of what are known to every one, it will happen to say that there are many definitions of the same thing, since some things are more known to some persons, and not the same to all, so that there would be a different definition to be given to each person, if it were necessary that definition should he framed from things more known to each severally. Further, to the same persons at a certain time, certain things are more known, at first indeed sensibles, but the reverse when they become more accurate, so that neither would the same definition have to be given to the same person, by those who say that a definition must be given through things more known to each. Clearly, then, we must not define through such things, but through those that are simply more known, since thus only would one and the same definition be always produced. Perhaps indeed what is simply known is not that which is known to all, but that (which is known) to those who have their intellect well disposed, just as what is simply wholesome is that which is so, to those whose bodies are in a good state. Hence it is necessary accurately to explain each of these, and to use them in discussion as may be expedient, but most confessedly is it possible to subvert definition, if it be neither framed from things simply more known, nor from those (which are so) to us.
One mode then (of proving) that it is not through things more known, is when the prior is manifested through the posterior, as we observed before; another, if the definition of what is at rest and definite, is a sign to us through the indefinite and through what is in motion, since the permanent and definite are prior to the indefinite, and to what is in motion.
The modes indeed (of showing a definition to be) not from things prior, are three, first, if the opposite is defined through the opposite, as good through evil, for opposites are naturally simultaneous. Still to some there seems to be the same science of both, so that the one is not more known than the other; nevertheless, we must bear in mind that some things perhaps it is impossible to define otherwise, as the double without the half, and whatever things are enunciated relatively per se, for in all these there is the same essence from their having relation in a certain re-
