All this, however, does not mean that a man can well be ‘in love’ with two women, for instance, at the same time. To love is a very different thing from being ‘in love’; and the latter indicates a torrent-rush of feeling which necessarily can only move towards one person at a time. (A standing flood of water may embrace and surround several islands, but it cannot very well _flow_ in more than one direction at once.) But this torrent-rush does not last forever, and in due time it subsides into the quiescent and lake-like stage—unless indeed it runs itself out and disappears altogether. Against this running out and disappearance it is part of the Art of Love to be able to guard. It has sometimes been argued that familiarity is of necessity fatal; and that it is useless to contend against this sinister tendency implanted in the very nature of love itself. But this contention contains only a very partial truth. It is true that in physical love there is a certain physical polarity which, like electric polarity, tends to equate itself by contact. The exchange of essences—which we saw as a chief phenomenon of conjugation, from the protozoa upwards—completes itself in any given case after a given time; and after that becomes comparatively quiescent. The same with the exchange of mental essences. Two people, after years, cease to exchange their views and opinions with the same vitality as at first; they lose their snap and crackle with regard to each other—and naturally, because they now know each other’s minds perfectly, and have perhaps modified them mutually to the point of likeness. But this only means, or should mean in a healthy case, that their interest in each other has passed into another plane, that the _venue_ of Love has been removed to another court. If something has been lost in respect of the physical rush and torrent, and something in respect of the mental breeze and sparkle, great things have been gained in the ever-widening assurance and confidence of spiritual unity, and a kind of lake-like calm which indeed reflects the heavens. And under all, still in the depths, one may be conscious of a subtle flow and interchange, yet going on between the two personalities and relating itself to some deep and unseen movements far down in the heart of Nature.