Happy marriages are well known to be rare; just because it lies in the nature of marriage that its chief end is not the present but the coming generation.
 Arthur Schopenhauer, The World as Will and Representation (1819). copy citation

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Author Arthur Schopenhauer
Source The World as Will and Representation
Topic marriage present
Date 1819
Language English
Reference
Note Translated by R. B. Haldane and J. Kemp
Weblink http://www.gutenberg.org/files/40868/40868-h/40868-h.html

Context

“The physical, moral, or intellectual deficiency of the nature of most men may to some extent have its ground in the fact that marriages are ordinarily entered into not from pure choice and inclination, but from all kinds of external considerations, and on account of accidental circumstances. If, however, besides convenience, inclination is also to a certain extent regarded, this is, as it were, an agreement with the genius of the species. Happy marriages are well known to be rare; just because it lies in the nature of marriage that its chief end is not the present but the coming generation. However, let me add, for the consolation of tender, loving natures, that sometimes passionate sexual love associates itself with a feeling of an entirely different origin—real friendship based upon agreement of disposition, which yet for the most part only appears when sexual love proper is extinguished in its satisfaction.” source