Imagine the world so greatly magnified that particles of light look like twenty-four-pound cannon balls.

To read means to borrow; to create out of one s readings is paying off one's debts.

A man has virtues enough if he deserves pardon for his faults on account of them.

The natural scientists of the previous age knew less than we do and believed they were very close to the goal: we have taken very great steps in its direction and now discover we are still very far away from it. With the most rational philosophers an increase in their knowledge is always attended by an increased conviction of their ignorance.

Nothing is more conducive to peace of mind than not having any opinion at all.

Of all the inventions of man I doubt whether any was more easily accomplished than that of a Heaven.

I have often noticed that when people come to understand a mathematical proposition in some other way than that of the ordinary demonstration, they promptly say, "Oh, I see. That's how it must be." This is a sign that they explain it to themselves from within their own system.