Men must work, and women must weep.

Therefore, let us be patient, patient; and let God our Father teach His own lesson, His own way. Let us try to learn it well and quickly; but do not let us fancy that He will ring the school-bell, and send us to play before our lesson is learnt.

Nature's deepest laws, her only true laws, are her invisible ones.

You must not say that this cannot be, or that that is contrary to nature. You do not know what Nature is, or what she can do; and nobody knows; not even Sir Roderick Murchison, or Professor Huxley, or Mr. Darwin, or Professor Faraday, or Mr. Grove, or any other of the great men whom good boys are taught to respect. They are very wise men; and you must listen respectfully to all they say: but even if they should say, which I am sure they never would, 'That cannot exist. That is contrary to nature,' you must wait a little, and see; for perhaps even they may be wrong.

Take comfort, and recollect however little you and I may know, God knows; He knows Himself and you and me and all things; and His mercy is over all His works.

You must not talk about 'ain't and can't' when you speak of this great wonderful world round you, of which the wisest man knows only the very smallest corner, and is, as the great Sir Isaac Newton said, only a child picking up pebbles on the shore of a boundless ocean.

[At the end of the story, its main character, Tom] is now a great man of science, and can plan railroads, and steam-engines, and electric telegraphs, and rifled guns, and so forth; and knows everything about everything, except why a hen's egg don't turn into a crocodile, and two or three other little things that no one will know till the coming of the Cocqcigrues.