The reason is the fact that love cannot help loving and uniting itself so as to be loved in return. This and nothing else is its essence and life. Women are by birth forms of love, and the men with whom they unite themselves to be loved in return are forms for reception. Moreover, love is continuously in action; it is like heat, flame and fire, which cease to exist if they are prevented from acting. That is why the wife's inclination to unite a man to herself is constant and permanent. But a man does not have a similar inclination towards his wife, because a man is not a form of love, but is only a receiver of love. His receptivity comes and goes as worries interfere, as the mind wavers between warmth and chill for various reasons, and as bodily strength increases and decreases. Since these factors are not constant and do not recur in a regular pattern, it follows that the inclination towards this linking is inconstant and fluctuating in the case of men.