"The wren goes to't and the small gilded fly does lecher in my sight." […] "The fitchew nor the soiled horse goes to't with a more ritous appetite. Down from the waist they are Centaurs, though women all above. But to the girdle do the gods inherit. Beneath is all the fiend's. There's hell, there's darkness, there is the sulphurous pit, burning scalding, stench, consumption; fie, fie, fie, pain, pain! Give me an ounce of civet, good apothecary, to sweeten my imagination." (13.97)
John delivers these scathing lines while Lenina is in the bathroom naked, having just been turned down for sex. Basically, Lear condemns the vagina as being the hot and sulphurous pit of hell.