If you only have a hammer, you tend to see every problem as a nail.

I suppose it is tempting, if the only tool you have is a hammer, to treat everything as if it were a nail.

One's only rival is one's own potentialities. One's only failure is failing to live up to one's own possibilities. In this sense, every man can be a king, and must therefore be treated like a king.

You don't need a $30 hammer to nail in a picture.

If all you have is a hammer, everything looks like a nail.

If you think only of evil, then you become pessimistic and hopeless like Freud. But if you think there is no evil, then you're just one more deluded Pollyanna.