While my interest in natural history has added very little to my sum of achievement, it has added immeasurably to my sum of enjoyment in life.

The difference between God and the historians consists above all in the fact that God cannot alter the past.

To be proud of virtue is to poison oneself with the antidote.

Whenever it is in any way possible, every boy and girl should choose as his life work some occupation which he should like to do anyhow, even if he did not need the money.

When life itself seems lunatic, who knows where madness lies? Perhaps to be too practical may be madness. To surrender dreams, this may be madness. To seek treasures where there is only trash...Too much sanity may be madness, and maddest of all is to see life as it is and not as it should be.

My kittens look at me like little angels, and always after doing something especially devilish.

We judge ourselves by what we are capable of doing, while others judge us by what we have already done.

The man who views the world at 50 the same as he did at 20 has wasted 30 years of his life.

From what we get, we can make a living; what we give, however, makes a life.

The first casualty when war comes is truth.