Man is torn away from his primary union with nature

Man is torn away from his primary union with nature, which characterizes animal existence. Having at the same time reason and imagination, he is aware of his aloneness and separateness; of his powerlessness and ignorance; of the accidentalness of his birth and death. He could not face this state of being for a second if he could not find new ties with his fellow man which replace the old ones regulated by instincts. Even if all his physiological needs were satisfied, he would experience his state of aloneness and individuation as a prison from which he had to break in order to preserve his sanity. (...) the necessity to unite with other living beings, to be related to them, is an imperative need on the fulfillment of which man's sanity depends. This need is behind all phenomena which constitute the whole gamut of intimate human relations, of all passions which are called love in the broadest sense of the word.
Erich Fromm, The Sane Society