It was one thing to have guessed it, another to have had that guess confirmed beyond possibility of refutation.

As three laws were good enough for Newton, I have modestly decided to stop there.

He was moving through a new order of creation, of which few men had ever dreamed. Beyond the realms of sea and land and air and space lay the realms of fire, which he alone had been privileged to glimpse. It was too much to expect that he would also understand.

As our own species is in the process of proving, one cannot have superior science and inferior morals. The combination is unstable and self-destroying.

The best measure of a man's honesty isn't his income tax return. It's the zero adjust on his bathroom scale.

It must be wonderful to be seventeen, and to know everything.

It will be possible in a few more years to build radio controlled rockets which can be steered into such orbits beyond the limits of the atmosphere and left to broadcast scientific information back to the Earth. A little later, manned rockets will be able to make similar flights with sufficient excess power to break the orbit and return to Earth. (1945) [Predicting communications satellites.]