If I had not been so great an invalid, I should not have done so much as I have accomplished.

The plow is one of the most ancient and most valuable of man's inventions; but long before he existed the land was in fact regularly plowed, and still continues to be thus plowed by earthworms. It may be doubted whether there are many other animals which have played so important a part in the history of the world, as have these lowly organized creatures.

Nothing is easier than to admit in words the truth of the universal struggle for life, or more difficult - at least I have found it so - than constantly to bear this conclusion in mind...We behold the face of nature bright with gladness...We do not see, or we forget, that the birds which are idly singing round us mostly live on insects and seeds, and are thus constantly destroying life.

I have been speculating last night what makes a man a discoverer of undiscovered things; and a most perplexing problem it is. Many men who are very clever - much cleverer than the discoverers - never originate anything.

We have happy days, remember good dinners.

Building a better mousetrap merely results in smarter mice.

The young blush much more freely than the old but not during infancy, which is remarkable, as we know that infants at a very early age redden from passion.