The part an actor played on stage was once written on a separate roll of paper.

The implications of these considerations justify the statement that all empirically verifiable knowledge even the commonsense knowledge of everyday life - involves implicitly, if not explicitly, systematic theory in this sense.

But the fact a person denies that he is theorising is no reason for taking him at his word and failing to investigate what implicit theory is involved in his statements.

That is, a system starts with a group of interrelated propositions which involve reference to empirical observations within the logical framework of the propositions in question.