In Act 4, Scene 6, the mad king expresses his disgust with women, obviously inspired by his recollection that it was his lust and copulation that produced Goneril and Regan, the two daughters who have made a fool of him with their false protestations of love and who have taken everything away from him, leaving him a dirty, homeless wretch.
Down from the waist they are Centaurs, Though women all above: But to the girdle do the gods inherit, Beneath is all the fiends'; There's hell, there's darkness, there's the sulphurous pit, Burning, scalding, stench, consumption; fie, fie, fie! pay, pah!
The pessimistic German philosopher Arthur Schopenhauer (1788-1860) has expressed his own unfavorable opinion of women and copulation as follows:
However, it might even seem to us that here the devil wanted merely to hide his game, for copulation is his currency and the world his kingdom. For has it not been observed how illico post coitum cachinnus auditur Diaboli? [‘Directly after copulation the devil’s laughter is heard.’] Seriously speaking, this is due to the fact that sexual desire, especially when through fixation on a definite woman it is concentrated to amorous infatuation, is the quintessence of the whole fraud of this noble world; for it promises so unspeakably, infinitely, and excessively much, and then performs so contemptibly little.
In Shakespeare's famous Sonnet 129, he writes:
Th' expense of spirit in a waste of shame Is lust in action...
Shakespeare continues, "Enjoyed no sooner but despised straight." He seems to be expressing the same thought as Schopenhauer does in saying "for it [sexual intercourse] promises so unspeakably, infinitely, and excessively much, and then performs so contemptibly little."