Anything capable of being imagined will one day be made reality.

I am very bad at expressing tender sentiments. The very word 'love' frightens me.

Science, my boy, is composed of errors, but errors that it is right to make, for they lead step by step to the truth.

In spite of the opinions of certain narrow-minded people who would shut up the human race upon this globe, we shall one day travel to the Moon, the planets, and the stars with the same facility, rapidity and certainty as we now make the ocean voyage from Liverpool to New York.

External objects produce decided effects upon the brain. A man shut up between four walls soon loses the power to associate words and ideas together. How many prisoners in solitary confinement become idiots, if not mad, for want of exercise for the thinking faculty!

I looked on, I thought, I reflected, I admired, in a state of stupefaction not altogether unmingled with fear!

[we see that] science is eminently perfectible, and that each theory has constantly to give way to a fresh one.