Indeed, where human beings are concerned we do not have the precise behaviour-patterns which are to be found among other animals, and instinct in that sense is replaced by something rather different. What we have with human beings is first of all a dissatisfaction leading to activities of a more or less random and imperfect sort, but arriving gradually, more or less by accident, at an activity which gives satisfaction and which is therefore repeated. What is instinctive is thus not so much the finished activity as the impulse to learn it, motives alone operates where the part of the father in generation is not known.
Source: Bertrand Russell :Marriage and Morals, 1929
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