If it can't be expressed in figures, it is not science; it is opinion. It has long been known that one horse can run faster than another - but which one? Differences are crucial.

What are the facts? Again and again and again – what are the facts? Shun wishful thinking, ignore divine revelation, forget what “the stars foretell,” avoid opinion, care not what the neighbors think, never mind the unguessable “verdict of history” – what are the facts, and to how many decimal places? You pilot always into an unknown future; facts are your single clue. Get the facts!

When the citizens of a nation will no longer volunteer to defend it, then it is probably not worth saving. No nation has the right to survive with conscript troops, and in the long run, no nation ever has.

No matter where or what, there are makers, takers, and fakers.

Men are not potatoes!

Most people can't think, most of the remainder won't think, and the small fraction who do think mostly can't do it very well.

The second best thing about space travel is that the distances involved make war very difficult, usually impractical, and almost always unnecessary. This is probably a loss for most people, since war is our race's most popular diversion, one which gives purpose and color to dull and stupid lives. But it is a great boon to the intelligent man who fights only when he must-never for sport.