“Men act like brutes in so far as the sequences of their perceptions arise through the principle of memory only, like those empirical physicians who have mere practice without theory.”

If you have a clear idea of a soul, you will have a clear idea of a form; for it is of the same genus, though a different species.

Reality cannot be found except in One single source, because of the interconnection of all things with one another.

In symbols one observes an advantage in discovery which is greatest when they express the exact nature of a thing briefly and, as it were, picture it; then indeed the labor of thought is wonderfully diminished.

I hold that it is only when we can prove everything we assert that we understand perfectly the thing under consideration.

The present is great with the future.

Indeed in general I hold that there is nothing truer than happiness, and nothing happier and sweeter than truth.

I also take it as granted that every created thing, and consequently the created monad also, is subject to change, and indeed that this change is continual in each one.

A great doctor kills more people than a great general.

The past is pregnant with the present.

There is no way in which a simple substance could begin in the course of nature, since it cannot be formed by means of compounding.

What is what must be.

In whatever manner God created the world, it would always have been regular and in a certain general order. God, however, has chosen the most perfect, that is to say, the one which is at the same time the simplest in hypothesis and the richest in phenomena.

The knowledge which we have acquired ought not to resemble a great shop without order, and without an inventory; we ought to know what we possess, and be able to make it serve us in need.

Nature does not make leaps.

It is unworthy of excellent men to lose hours like slaves in the labor of calculation which could be relegated to anyone else if machines were used.

I am so in favor of the actual infinite that instead of admitting that Nature abhors it, as is commonly said, I hold that Nature makes frequent use of it everywhere, in order to show more effectively the perfections of its Author.

Why should the actions of the imagination not be as real as those of perception?

There is no truth. There is only perception.

Perception is a tool that’s pointed on both ends.

Great literature should do some good to the reader: must quicken his perception though dull, and sharpen his discrimination though blunt, and mellow the rawness of his personal opinions.

The brain is the highest of the organs in position, and it is protected by the vault of the head; it has no flesh or blood or refuse. It is the citadel of sense-perception.

Literature expresses itself by abstractions, whereas painting, by means of drawing and colour, gives concrete shape to sensations and perceptions.

The brain is the citadel of sense perception.

Other people’s ideas of us are dependent largely on what they’ve hoped for.