In the early 19th century, many of the academic subjects of our time had not taken shape. Then, to be a polymath, was a difficult ideal, but still we tend to think that some succeeded. Now, after two centuries with its growth, differentiation and shifts of academic subjects things have changed dramatically. Subjects characterized by a prolonged professional training as well as sustained practical experience are almost sealed off to academics from other fields. This is especially so in the natural sciences, where someone trained in physics would not think of venturing into, for instance, pharmacy, where he has no training. The demands and standards of one discipline cannot be passed by and interdisciplinarity here invariably means to cooperate with experts than to dabble into the other field oneself
