Such remarks are not infrequently coupled with another remark which goes more deeply to the root of the matter: "You should not show your indifference so plainly." In other words pretence is expected when actual love has died. And indeed nothing else could be expected logically by such illogical lovers, unless of course a deep affection, which may have grown between two human beings in the course of many years of life partnership, successfully masks the passing of the peculiar fascination which differentiates love proper from any other human feeling. =Love and Affection.= We may love a human being more than ourselves, enjoy infinitely his presence, delight in giving to him mental and physical happiness, lavish on him a thousand caresses and yet not experience the flash of desire which leads compulsively toward complete physical communion with that human being. A simile from the animal world will make my meaning clearer. A large number of animals "enjoy" light but only a small number of them are so "fascinated" by light that they cannot resist a "craving" to fly toward a light, contact with which may mean death to them. Only that small minority can be called in scientific jargon "positively phototropic," in sentimental parlance "hopelessly in love" with light. All animals are affected in some fashion by an electric current passing thru their bodies, but only a minority of them are so affected by it that they must, whether they wish it or not, face the positive electrode, as a lover fascinated by the face of his sweetheart. Only these can be characterised as "positively galvanotropic." =Erotropism.= Likewise a hundred men may be charmed by the sight of a woman. Only one or two from their number may feel compelled to seek complete union with her regardless of the obstacles to be surmounted, of the criticism their actions may arouse, of the expenditure of time, money and energy the adventure may entail. Only this minority may be considered as "positively erotropic." In other words it is the primal compulsion which nature uses to assure the continuance of the race and which I might designate as "erotropism" which must be considered the basis for a discussion of love. Love as commonly understood or misunderstood at the present day, is a series of variations on the theme of erotropism, variations due to the complication of modern civilisation and the restrictions placed upon all biological phenomena by the necessities of life in communities. =What is the Heart?= The reader will notice that I have thus far avoided any mention of the "heart" altho that organ is commonly identified with the various emotions of love. Physiologically speaking, the heart is no more vitally concerned with love than with any other disturbing feeling and emotion. Love may at times cause our heart to beat wildly, but so does strong coffee, so does acute indigestion, so does blood poisoning, so does any sort of violent fear.