Sometimes a scream is better than a thesis.
A theory has only the alternative of being right or wrong.
A model has a third possibility: it may be right, but irrelevant.
One will only be free when one plays and one's society will become a piece of art". - Herbert Marcuse "Play is a phenomenon of nature and has directed the course of the world from the beginning of time: the formation of matter, its organization into living structures as well as the social behavior of man.
In theory, there is no difference between theory and practice. But, in practice, there is.
A theory can be proved by experiment; but no path leads from experiment to the birth of a theory.