Perhaps the main reason why no one has anticipated me in writing a book showing that Love is an exclusively modern sentiment, and tracing its gradual development, is because no distinction has been commonly made between Romantic Love and Conjugal Affection, though they differ as widely as maternal love and friendship. The occurrence of noble examples of conjugal attachment as far back as Homer has obscured the fact that pre-nuptial or Romantic Love is almost as modern as the telegraph, the railway, and the electric light. Two thousand and four hundred years ago the Greek philosopher Empedokles taught that there are four elements—fire, air, water, earth—which remain unchanged amid all combinations. Chemistry has long since shown that these supposed elements are compounds, and that the number of real elements is much larger. In a similar way the tender or family emotions have been gradually distinguished from one another. Among the ancient Greeks φιλότης meant both friendship and sexual love, which, as we have seen, they strangely confounded, both in theory and in practice. To-day we distinguish not only between friendship and sexual love, but between the two phases of sexual love—Romantic and Conjugal Affection—the former of which was unknown to the Greeks. We do this not only because, as in the case of the chemical elements, our knowledge has become more precise and subtle, but because these emotions have been gradually developed, and have assumed different characteristics, so that it would be difficult at present to mistake one for the other. As regards the difference between Conjugal and Romantic Love, however, the current conceptions are not yet so clear and definite; many good folks being, in fact, inclined to frown upon the suggestion that there is any such difference. Yet it is useless for them to endeavour, with well-meant hypocrisy, to impress upon the young the notion that Love is unchangeable, since no one who keeps his eyes open can help noticing how differently married couples behave from lovers. In marriage the dazzling blue flame of Romantic Love gradually grows smaller and dies away. But the coals may retain their glow and perchance keep the heart warmer than the former flickering flames of Love.