Necessity is the theme and the inventress, the eternal curb and law of nature. - Leonardo da Vinci

To me it seems that those sciences are vain and full of error which are not born of experience, mother of all certainty, first-hand experience which in its origins, or means, or end has passed through one of the five senses. And if we doubt the certainty of everything which passes through the senses, how much more ought we to doubt things contrary to these senses – ribelli ad essi sensi – such as the existence of God or of the soul or similar things over which there is always dispute and contention. And in fact it happens that whenever reason is wanting men to cry out against one another, which does not happen with certainties. For this reason we shall say that where the cry of controversy is heard, there is no true science, because the truth has one single end and when this is published, argument is destroyed for ever.

The instant does not have time; and time is made from the movement of the instant.

First, of things relating to animals; secondly, of irrational creatures; thirdly of plants; fourthly, of ceremonies; fifthly, of manners; sixthly, of cases or edicts or quarrels; seventhly, of cases that are impossible in nature [paradoxes], as, for instance, of those things which, the more is taken from them, the more they grow. And reserve the great matters till the end, and the small matters give at the beginning.