Robert A. Heinlein

People who go broke in a big way never miss any meals. It is the poor jerk who is shy a half slug who must tighten his belt.

If you would know a man, observe how he treats a cat.

Boats and ships are female because they are beautiful, lovable, expensive—and unpredictable.

What a wonderful world it is that has girls in it!

Sex should be friendly. Otherwise stick to mechanical toys; it's more sanitary.

Place your clothes and weapons where you can find them in the dark.

There is solemn satisfaction in doing the best you can for eight billion people. Perhaps their lives have no cosmic significance, but they have feelings. They can hurt.

Being generous is inborn; being altruistic is a learned perversity. No resemblance.

If you happen to be one of the fretful minority who can do creative work, never force an idea; you'll abort it if you do. Be patient and you'll give birth to it when the time is ripe. Learn to wait.

There is only one way to console a widow. But remember the risk.

Throughout history, poverty is the normal condition of man. Advances which permit this norm to be exceeded — here and there, now and then — are the work of an extremely small minority, frequently despised, often condemned, and almost always opposed by all right-thinking people. Whenever this tiny minority is kept from creating, or (as sometimes happens) is driven out of a society, the people then slip back into abject poverty.
This is known as "bad luck."

No state has an inherent right to survive through conscript troops and, in the long run, no state ever has. Roman matrons used to say to their sons: "Come back with your shield, or on it." Later on, this custom declined. So did Rome.

Patriotism is not sentimental nonsense. Nor something dreamed up by demagogues. Patriotism is as necessary a part of man's evolutionary equipment as are his eyes, as useful to the race as eyes are to the individual.

I believe in —  I am proud to belong to —  the United States. Despite shortcomings, from lynchings to bad faith in high places, our nation has had the most decent and kindly internal practices and foreign policies to be found anywhere in history.
And finally, I believe in my whole race. Yellow, white, black, red, brown — in the honesty, courage, intelligence, durability … and goodness … .of the overwhelming majority of my brothers and sisters everywhere on this planet. I am proud to be a human being. I believe that we have come this far by the skin of our teeth, that we always make it just by the skin of our teeth — but that we will always make it … survive … endure. I believe that this hairless embryo with the aching, oversize brain case and the opposable thumb, this animal barely up from the apes, will endure — will endure longer than his home planet, will spread out to the other planets, to the stars, and beyond, carrying with him his honesty, his insatiable curiosity, his unlimited courage — and his noble essential decency.
This I believe with all my heart.

Certainly the game is rigged. Don't let that stop you; if you don't bet, you can't win.

Jealousy is a disease, love is a healthy condition. The immature mind often confuses one for the other, or assumes the greater the love, the greater the jealousy. In fact they are almost incompatible; both at once produce unbearable turmoil.

Everybody lies about sex.

Correct morality can only be derived from what man is — not from what do-gooders and well-meaning aunt Nellies would like him to be.

Most "scientists" are bottle washers and button sorters.

When a place gets crowded enough to require ID's, social collapse is not far away. It is time to go elsewhere. The best thing about space travel is that it made it possible to go elsewhere.