Classical science in its diverse disciplines, be it chemistry, biology, psychology or the social sciences, tried to isolate the elements of the observed universe - chemical compounds and enzymes, cells, elementary sensations, freely competing individuals, what not — expecting that, by putting them together again, conceptually or experimentally, the whole or system - cell, mind, society - would result and be intelligible. Now we have learned that for an understanding not only the elements but their interrelations as well are required.

p. xix - General System Theory (1968)