A principle is a flexible guideline that can help you to solve a problem you have never encountered before.

If you really understand the principles of physics, for instance, you can solve a new problem simply by working backward.

Ultralearning (Scott H. Young, 2019)

Principles can provide guidance and help you make sense of the world, even if they don’t articulate exactly how to solve a particular challenge. (See also: Wrong but useful.)

Design principles