The chief difficulty for men, as for other animals, is adaptation to new circumstances. The great reptiles of the days before men, who might have seemed invincible, perished from a change of climate. Innumerable kinds of animals have become extinct through specialising on weapons of offence, such as too many horns, which left them inadequate energy for ordinary living. ...
The conditions of universal prosperity are quite simple and well known, but they involve changes in our habits of feeling, and ...
Source: Bertrand Russell : Mortals and Others, v.1, 1975
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