Whatever torch we kindle, and whatever space it may illuminate, our horizon will always remain encircled by the depth of night.

A man's knowledge may be said to be mature, in other words, when it has reached the most complete state of perfection to which he, as an individual, is capable of bringing it, when an exact correspondence is established between the whole of his abstract ideas and the things he has actually perceived for himself. His will mean that each of his abstract ideas rests, directly or indirectly, upon a basis of observation, which alone endows it with any real value; and also that he is able to place every observation he makes under the right abstract idea which belongs to it.

Reason is feminine in nature; it can only give after it has received.

It is the courage to make a clean breast of it in the face of every question that makes the philosopher. He must be like Sophocles' Oedipus, who, seeking enlightenment concerning his terrible fate, pursues his indefatigable inquiry even though he divines that appalling horror awaits him in the answer. But most of us carry with us the Jocasta in our hearts, who begs Oedipus, for God's sake, not to inquire further.

In our early youth we sit before the life that lies ahead of us like children sitting before the curtain in a theatre, in happy and tense anticipation of whatever is going to appear. Luckily we do not know what really will appear.

The alchemists in their search for gold discovered many other things of greater value.

Ordinary people merely think how they shall 'spend' their time; a man of talent tries to 'use' it.