Depend upon it there comes a time when for every addition of knowledge you forget something that you knew before. It is of the highest importance, therefore, not to have useless facts elbowing out the useful ones.

Well, I'm a bacteriologist, you know. I live in a nine-hundred-diameter microscope. I can hardly claim to take serious notice of anything that I can see with my naked eye.

I have frequently gained my first real insight into the character of parents by studying their children.

horses: dangerous on both ends and crafty in the middle

It is a capital mistake to theorize before you have all the evidence. It biases the judgment.

We surely know by some nameless instinct more about our futures than we think we know.

Well, sir, let us do what we can to curtail this visit, which can hardly be agreeable to you, and is inexpressibly irksome to me.