Our achievements of today are but the sum total of our thoughts of yesterday. You are today where the thoughts of yesterday have brought you and you will be tomorrow where the thoughts of today take you.

The end point of rationality is to demonstrate the limits of rationality.

Symmetry is what we see at a glance; based on the fact that there is no reason for any difference.

We know that there is an infinite, and we know not its nature. As we know it to be false that numbers are finite, it is therefore true that there is a numerical infinity. But we know not of what kind; it is untrue that it is even, untrue that it is odd; for the addition of a unit does not change its nature; yet it is a number, and every number is odd or even (this certainly holds of every finite number). Thus we may quite well know that there is a God without knowing what He is.

When we see an effect happen always in the same manner, we infer that it takes place by a natural necessity; as, for instance, that the sun will rise to morrow; but nature often deceives us, and will not submit to its own rules.

Parents fear the destruction of natural affection in their children. What is this natural principle so liable to decay? Habit is a second nature, which destroys the first. Why is not custom nature? I suspect that this nature itself is but a first custom, as custom is a second nature.

Man's true nature being lost, everything becomes his nature; as, his true good being lost, everything becomes his good.