By the data to date, there is only one animal in the Galaxy dangerous to man -- man himself. So he must supply his own indispensable competition. He has no enemy to help him.
Robert A. HeinleinThe mind's ability to rationalize it's own shortcomings is unlimited; I am no exception.
Robert A. HeinleinMan has no moral instinct. He is not born with moral sense. You were not born with it, I was not - and a puppy has none. We acquire moral sense, when we do, through training, experience, and hard sweat of the mind.
Robert A. HeinleinNo matter what I said they insisted on thinking of God as something outside themselves. Something that yearns to take every indolent moron to His breast and comfort him. The notion that the effort has to be their own . . . and that the trouble they are in is all their own doing . . . is one that they can't or won't entertain.
Robert A. Heinlein