How then is perfection to be sought? Wherein lies our hope? In education, and in nothing else.

Always regard every man as an end in himself, and never use him merely as a means to your ends [i.e., respect that each person has a life and purpose that is their own; do not treat people as objects to be exploited].

Fallacious and misleading arguments are most easily detected if set out in correct syllogistic form.

The light dove, in free flight cutting through the air the resistance of which it feels, could get the idea that it could do even better in airless space. Likewise, Plato abandoned the world of the senses because it posed so many hindrances for the understanding, and dared to go beyond it on the wings of the ideas, in the empty space of pure understanding.

A single line in the Bible has consoled me more than all the books I ever read besides.

God, freedom, and immortality are untenable in the light of pure reason.

cruelty to animals is contrary to man's duty to himself, because it deadens in him the feeling of sympathy for their sufferings, and thus a natural tendency that is very useful to morality in relation to other human beings is weakened.