To the man who only has a hammer, everything he encounters begins to look like a nail.

Perspective

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

Self-knowledge

Become aware of internal, subjective, sub-verbal experiences, so that these experiences can be brought into the world of abstraction, of conversation, of naming, etc. with the consequence that it immediately becomes possible for a certain amount of control to be exerted over these hitherto unconscious and uncontrollable processes.