The most important advance in the next fifty years will be in the realm of the spiritual - dealing with the spirit of thought.

From a mathematical standpoint it is possible to have infinite space. In a mathematical sense space is manifoldness, or combinations of numbers. Physical space is known as the 3-dimension system. There is the 4-dimension system, the 10-dimension system.

The scientist is not much given to talking of the riddle of the universe. "Riddle" is not a scientific term. The conception of a riddle is "something which can he solved." And hence the scientist does not use that popular phrase. We don't know the why of anything. On that matter we are no further advanced than was the cavedweller. The scientist is contented if he can contribute something toward the knowledge of what is and how it is.

No man really becomes a fool until he stops asking questions.

Mathematics is the most exact science, and its conclusions are capable of absolute proof. But this is so only because mathematics does not attempt to draw absolute conclusions. All mathematical truths are relative, conditional. In E. T. Bell Men of Mathematics, New York: Simona and Schuster, 1937.

[I predict] the electricity generated by water power is the only thing that is going to keep future generations from freezing. Now we use coal whenever we produce electric power by steam engine, but there will be a time when there'll be no more coal to use. That time is not in the very distant future. ... Oil is too insignificant in its available supply to come into much consideration.

The mercury light doesn't show red. It makes the blood in your skin look blue-black. But see how splendidly it brings out the green in the plants.