Size is not grandeur, and territory does not make a nation.

It is better to read a little and thoroughly than cram a crude undigested mass into my head, though it be great in quantity.

Not only does every animal live at the expense of some other animal or plant, but the very plants are at war.... The individuals of a species are like the crew of a foundered ship, and none but good swimmers have a chance of reaching the land.

The rung of a ladder was never meant to rest upon.

Protoplasm, simple or nucleated, is the formal basis of all life. It is the clay of the potter: which, bake it and paint it as hewill, remains clay, separated by artifice, and not by nature from the commonest brick or sun-dried clod.

It sounds paradoxical to say the attainment of scientific truth has been effected, to a great extent, by the help of scientific errors.

Life is like walking along a crowded street--there always seem to be fewer obstacles to getting along on the opposite pavement--and yet, if one crosses over, matters are rarely mended.