Manfred Eigen quotes:

A theory can be proved by experiment; but no path leads from experiment to the birth of a theory.

In theory, there is no difference between theory and practice. But, in practice, there is.

A theory has only the alternative of being right or wrong. A model has a third possibility: it may be right, but irrelevant.

Sometimes a scream is better than a thesis.

One will only be free when one plays and one's society will become a piece of art". - Herbert Marcuse