Rene Descartes

I confess that I have never found in my experience that anything which I once clearly understood could afterwards be called into doubt by me.

The greatest good is the knowledge of truth, and the greatest evil is error.

I would not advise anyone to read my books who has not the leisure and inclination to meditate seriously with me.

It is true that when I consider how many different beliefs there are among men, I find no reason to choose one rather than another.

For the mind is not nourished by anything but truth.

It is a mark of a truly great mind to be able to make a great discovery with few means.

I suppose therefore that all the things I see are false imaginations; I believe that nothing ever existed of all that my fallacious memory represents to me.

The greatest good is that which is most useful.

It is not enough to walk with great strides, it is necessary to walk in the right road.

I have never had any experience that was not accompanied by some thought.

To conquer myself rather than fortune, and to change my desires rather than the order of the world.

The long chains of simple and easy reasonings by means of which geometers are accustomed to reach the conclusions of their most difficult demonstrations, had led me to imagine that all things, the knowledge of which is open to man, are similarly dependent one upon another.

I feel within me a will that is far more extensive than my understanding.

The light of natural reason is not less certain than that of revelation.

I have never made any distinction between the sciences, but have always held that all are linked together, and that it is easier to learn them all at once than to learn one separately.

It is not enough to apply our mind to things, but we must also apply it to ourselves.

All that is solid melts into air.

To know what is true is to know what is good.

The mind is a substance whose whole essence or nature consists only of thinking.

The greatest good is to live without pain.