I think, therefore I am.

Once in one's life, everything should be called into doubt.

Divide each difficulty into as many parts as possible for a better solution.

I think, therefore I am.

The wise man is free from passions, not because he does not feel, but because his judgments are correct.

-- Chrysippus of Soli

The pleasant life is produced not by endless drinking and revelry but by sober reasoning.

-- Epicurus

Being all equal and independent, no one ought to harm another in his life, health, liberty, or possessions.

-- John Locke

The legal subordination of one sex to another is wrong in itself, and now one of the chief hindrances to human improvement.

-- John Stuart Mill

I have striven not to laugh at human actions, not to weep at them, nor to hate them, but to understand them.

-- Benedictus de Spinoza

Two things fill the mind with ever new and increasing admiration and reverence: the starry heavens above me and the moral law within me.

-- Immanuel Kant