Two important lessons of this chapter should, however, be carefully borne in mind; for though our search for Love has so far yielded only negative results, some light has been thrown on the general laws of Beauty in Nature. The lessons are:— (1) That there is in flowers a natural tendency towards Symmetry of Form, all normal irregularities being due to the agency of insects and birds. (2) That the superior Beauty of one flower over another is due to its superior vitality or Health, which, again, is promoted by cross-fertilisation or intermarriage—the choosing of a mate not in the same but in another flower-bed. Regarding the beauty of flowers a further detail may be added. Some of the coloured lines on flowers are so placed as to guide the visiting bees to the nectar or honey. More complicated colour-patterns probably owe their existence to the advantage of having an easy means of recognition at a distance. It is well known that bees on any single expedition visit the flowers of one species only. Now it has been experimentally proved by Lubbock that bees can distinguish different colours; and, if we may judge by analogy with the human eye, they can distinguish colours at a greater distance than forms. Hence the advantage to each flower of having its own colours in its flag. IMPERSONAL AFFECTION From the sexual life of plants we ought to pass on to that of animals; but before doing so, it will be advisable to ascertain clearly what is meant by Romantic Love, and how it differs from other forms of affection, impersonal and personal; from the love for inanimate objects and for plants and animals; from the family affections—maternal, paternal, filial, brotherly, and sisterly love; from friendship; and from conjugal love. Love is the most attractive word in the language, as Heine and Oliver Wendell Holmes have remarked. Out of every half-dozen novels one is likely to have the word Love in its title, as a bait sure to catch readers. But whereas novelists always use this word in the sense of Romantic or pre-matrimonial Love, in common language it is vaguely used as a synonym for any kind of attachment, from that of Romeo to the schoolgirl who “just _loves_ caramels.” For the verb _to love_ there is perhaps no satisfactory and equally comprehensive substitute; but in place of the noun _love_ it is advisable, at least in a scientific work, to use the word Affection, which comprehends every form of love mentioned above. In the present work Love, with a capital L, always means Romantic Love.