One Of these aspects is the realm Of science and its applications. Its structures radiate the brilliant illuminations Of harmony and pure truth. The other is the dark domain Of political and social life. Its shaky edifices remain enveloped in illusions, errors, and hatreds, and furious struggles frequently lay them low. This striking contrast between the different domains Of the great civilisations is due to the fact that their structural elements do not Obey the same laws, and have no common measure. Social life is governed by needs, sentiments, and instincts bequeathed to us by heredity, which through Whole strata Of evolution represented the only guides Of conduct. In this domain, progressive evolution remains feeble. The feelings Of ambition, jealousy, ferocity, and hatred, which animated our first ancestors, remain unchanged.