If a man knows not life which he hath seen, how shall he know death, which he hath not seen?

You cannot have a thing "matter" by itself which shall have no motion in it, nor yet a thing "motion" by itself which shall exist apart from matter; you must have both or neither. You can have matter moving much, or little, and in all conceivable ways; but you cannot have matter without any motion more than you can have motion without any matter that is moving.

I believe that he was really sorry that people would not believe he was sorry that he was not more sorry.

If [science] tends to thicken the crust of ice on which, as it were, we are skating, it is all right. If it tries to find, or professes to have found, the solid ground at the bottom of the water it is all wrong. Our business is with the thickening of this crust by extending our knowledge downward from above, as ice gets thicker while the frost lasts; we should not try to freeze upwards from the bottom.

Nature. As the word is now commonly used it excludes nature's most interesting productions-the works of man. Nature is usually taken to mean mountains, rivers, clouds and undomesticated animals and plants. I am not indifferent to this half of nature, but it interests me much less than the other half.

He that complies against his will, Is of his own opinion still.

A man should have any number of little aims about which he should be conscious and for which he should have names, but he should have neither name for, nor consciousness concerning the main aim of his life.