Science, my lad, is made up of mistakes, but they are mistakes which it is useful to make, because they lead little by little to the truth.

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!

The colonists had no library at their disposal; but the engineer was a book which was always at hand, always open at the page which one wanted, a book which answered all their questions, and which they often consulted.

Well, I thought I was so tranquil! I need to give up that illusion! There is decidedly no rest to be had in this world.

No sooner is the rage of hunger appeased than it becomes difficult to comprehend the meaning of starvation. It is only when you suffer that you really understand.

Reality provides us with facts so romantic that imagination itself could add nothing to them.

At Kiel, as elsewhere, a day goes by somehow or other.