In the former case, our knowledge is the consequence of the existence of things, producing ideas in our minds by our senses: in the latter, knowledge is the consequence of the ideas (be they what they will) that are in our minds, producing there general certain propositions. Many of these are called AETERNAE VERITATES, and all of them indeed are so; not from being written, all or any of them, in the minds of all men; or that they were any of them propositions in any one's mind, till he, having got the abstract ideas, joined or separated them by affirmation or negation. But wheresoever we can suppose such a creature as man is, endowed with such faculties, and thereby furnished with such ideas as we have, we must conclude, he must needs, when he applies his thoughts to the consideration of his ideas, know the truth of certain propositions that will arise from the agreement or disagreement which he will perceive in his own ideas. Such propositions are therefore called ETERNAL TRUTHS, not because they are eternal propositions actually formed, and antecedent to the understanding that at any time makes them; nor because they are imprinted on the mind from any patterns that are anywhere out of the mind, and existed before: but because, being once made about abstract ideas, so as to be true, they will, whenever they can be supposed to be made again at any time, past or come, by a mind having those ideas, always actually be true. For names being supposed to stand perpetually for the same ideas, and the same ideas having immutably the same habitudes one to another, propositions concerning any abstract ideas that are once true must needs be ETERNAL VERITIES. CHAPTER XII. OF THE IMPROVEMENT OF OUR KNOWLEDGE 1. Knowledge is not got from Maxims. IT having been the common received opinion amongst men of letters, that MAXIMS were the foundation of all knowledge; and that the sciences were each of them built upon certain PRAECOGNITA, from whence the understanding was to take its rise, and by which it was to conduct itself in its inquiries into the matters belonging to that science, the beaten road of the Schools has been, to lay down in the beginning one or more GENERAL PROPOSITIONS, as foundations whereon to build the knowledge that was to be had of that subject. These doctrines, thus laid down for foundations of any science, were called PRINCIPLES, as the beginnings from which we must set out, and look no further backwards in our inquiries, as we have already observed. 2. (The Occasion of that Opinion.) One thing which might probably give an occasion to this way of proceeding in other sciences, was (as I suppose) the good success it seemed to have in MATHEMATICS, wherein men, being observed to attain a great certainty of knowledge, these sciences came by pre-eminence to be called [word in Greek], and [word in Greek], learning, or things learned, thoroughly learned, as having of all others the greatest certainty, clearness, and evidence in them.