Heaven is not as narrowly literal-minded as hell.

He had seen too much of the cosmos to have any great faith in man's ability to understand it.

In Harvest of Stars, there is this notion, not original with me of course, that it will become possible to download at least the basic aspects of a human personality into a machine program.

A fanatic's willingness to kill or be killed in the service of a cause cannot prove the rightness of that cause.

Will none wipe the sneer off the face of the cosmos?

The fish that first ventured ashore had considerable practical problems.

A fanatic is a man who, when he's lost sight of his purpose, redoubles his effort.