Immanuel Kant was serious about the sanctity of sex within marriage. Deadly serious. An illegitimate child is denied all legal rights, and can be disposed of at will:
Legislation cannot remove the disgrace of an illegitimate birth … A child that comes into the world apart from marriage is born outside the law … and therefore outside the protection of the law. It has, as it were, stolen into the commonwealth (like contraband merchandise), so that the commonwealth can ignore its existence (since it was not right that it should have come to exist this way), and can therefore also ignore its annihilation …
In his Second Treatise of Civil Government John Locke claims that ninety-nine percent of the value derived from land come from the labour invested in it. The following is an argument he uses to elaborate on this point:
There cannot be a clearer demonstration of any thing, than several nations of the Americans are of this, who are rich in land, and poor in all the comforts of life; whom nature having furnished as liberally as any other people, with the materials of plenty, i.e. a fruitful soil, apt to produce in abundance, what might serve for food, raiment, and delight; yet for want of improving it by labour, have not one hundredth part of the conveniencies we enjoy …
For Jean-Jacques, the onset of involuntary (presumably nocturnal) emissions was an issue of considerable moral distress. Moreover, it was a problem that, in the hands of the susceptible, often led to terrible vice:
I returned from Italy a different person from the one who had gone there … I had preserved my physical but not by moral virginity. The progress of the years had been told upon me, and my restless temperament had at last made itself felt. Its first quite involuntary outbreak indeed had caused me some alarm about my health, a fact which illustrates better than anything else the innocence in which I had lived until then. Soon I was reassured, however, and learnt of that dangerous means of cheating Nature …