It was the Christian dogma and the sacramental and lifelong character of marriage which first caused the stamp of infamy to be impressed upon all other varieties of sexual intercourse. The religious marriage was in its very nature indissoluble; indeed, by forbidding mixed marriages (marriages between Christian and pagan) individual freedom was entirely prohibited. In contrast with this ancient religious view, the State, by the introduction of civil marriage, of mixed marriage (_vide supra_), and of divorce, has been compelled to make continually greater concessions to modern ideas, and =has already recognized in principle= that marriages limited in duration harmonize exceedingly well with the demands of civilization; that in general, as Lecky maintained, the recent changes in economic conditions have a much greater influence upon marriage and the forms of marriage than the ecclesiastical and mystical conception of the institution. Anyone who wishes to gain an insight into this very difficult problem of modern marriage must first obtain clear views in respect of certain peculiarities of individual human love, regarding the intimate connexion of which with the whole process of mental evolution we have already dealt in earlier chapters. Max Nordau has written a celebrated chapter on “The Lie of Marriage,”[167] and in the light of reality marriage is, in fact, often such a lie as he describes, especially in view of the fact that not less than 75 per cent. of modern marriages are so-called “marriages of convenience,” and in no sense are properly love-marriages.[168] But it is a well-known fact that these marriages of reason are often more enduring than love-marriages. This depends upon the nature of human love, which is by no means inalterable, =but changes in accordance with the various developmental phases of the individual, needs new incitements and new individual relationships=. In No. 14,919 of the _Neue Freie Presse_ of Vienna, March 6, 1906, there appeared among the advertisements a remarkable question, which was probably directed by a betrayed or deceived lover to his beloved: “Ewige Liebe--ewige Lüge?” “Eternal Love--Eternal Lie?” Love also, personal love, is transitory, like man himself, like the isolated individual. It differs in the different ages of life; it differs, too, according to its object for the time being. Eduard von Hartmann calls love a thunderstorm, which does not discharge in a single flash of lightning, but gradually discharges the electrical energy in several successive flashes, and after the discharge “there comes the cool wind, the heaven of consciousness clears once more, and we look round astonished at the fertilizing rain falling on the ground, and at the clouds fleeing towards the distant horizon.”