He who is not contented with what he has, would not be contented with what he would like to have.

...one thing I am ready to fight for as long as I can, in word and act: that is, that we shall be better, braver and more active men if we believe it right to look for what we don't know than if we believe there is no point in looking because what we don't know we can never discover.

If we pursue our habit of eating animals, and if our neighbour follows a similar path, will we need to go to war against our neighbour to secure greater pasturage, because ours will not be enough to sustain us, and our neighbour will have a similar need to wage war on us for the same reason.

Wisdom begins in wonder.

It is a base thing for a man to wax old in careless self-neglect before he has lifted up his eyes and seen what manner of man he was made to be, in the full perfection of bodily strength and beauty. But these glories are withheld from him who is guilty of self-neglect, for they are not wont to blaze forth unbidden.

The partisan when he is engaged in a dispute, cares nothing about the rights of the question, but is anxious only to convince his hearers of his own assertions.

If I can assign names as well as pictures to objects, the right assignment of them we may call truth, and the wrong assignment of them falsehood.