DefinitionöScience is systematized positive knowledge, what has been taken as such in different ages and in different places. TheoremöThe acquisition and systematization of positive knowledge are the only human activities which are truly cumulative and progressive.CorollaryöThe history of science is the only history which can illustrate the progress of mankind. In fact, progress has no definite and unquestionable meaning in other fields than the field of science.

-Sarton, George A
  The Study of the History of Science.