But the whole of this intolerance vanishes, temporarily or permanently, as the result of the formation of a group, and in a group. So long as a group formation persists or so far as it extends, individuals behave as though they were uniform, tolerate other people's peculiarities, put themselves on an equal level with them, and have no feeling of aversion towards them. Such a limitation of narcissism can, according to our theoretical views, only be produced by one factor, a libidinal tie with other people. Love for oneself knows only one barrier--love for others, love for objects.[37] The question will at once be raised whether community of interest in itself, without any addition of libido, must not necessarily lead to the toleration of other people and to considerateness for them. This objection may be met by the reply that nevertheless no lasting limitation of narcissism is effected in this way, since this tolerance does not persist longer than the immediate advantage gained from the other people's collaboration. But the practical importance of the discussion is less than might be supposed, for experience has shown that in cases of collaboration libidinal ties are regularly formed between the fellow-workers which prolong and solidify the relation between them to a point beyond what is merely profitable. The same thing occurs in men's social relations as has become familiar to psycho-analytic research in the course of the development of the individual libido. The libido props itself upon the satisfaction of the great vital needs, and chooses as its first objects the people who have a share in that process. And in the development of mankind as a whole, just as in individuals, love alone acts as the civilizing factor in the sense that it brings a change from egoism to altruism. And this is true both of the sexual love for women, with all the obligations which it involves of sparing what women are fond of, and also of the desexualised, sublimated homosexual love for other men, which springs from work in common. If therefore in groups narcissistic self-love is subject to limitations which do not operate outside them, that is cogent evidence that the essence of a group formation consists in a new kind of libidinal ties among the members of the group.