This is a passage from Still Life With Woodpecker by Tom Robbins.
There is lovemaking that is bad for a person, just as there is eating that is bad. That boysenberry cream pie form the Thrift-E Mart may appear inviting, may in fact, cause all nine hundred taste buds to carol from the tongue, but in the end, the sugars, the additives, the empty calories clog arteries, disrupt cells, generate fat, and rot teeth. Even potentially nourishing foods can be improperly prepared. There are wrong combinations and improper preparations in sex as well. Yes, one must prepare for a fuck – the way in which an enlightened priest prepares to celebrate mass, the way a great matador prepares for the ring: with intensification, with purification, with a conscious summoning of sacred power. And even that won’t work if the ingredients are poorly matched: oysters are delectable, so are strawberries, but mashed together…(?!) Every nutritious sexual recipe calls for at least a pinch of love, and the fucks that rate four-star rankings from both gourmets and health-food nuts use cupfuls. Not that sex should be regarded as therapeutic or to be taken for medicinal purposes – only a dullard would hang such a millstone around the nibbled neck of a lay – but to approach sex carelessly, shallowly, with detachment and without warmth is to dine night after night in erotic greasy spoons. In time, one’s palate will become insensitive, one will suffer (without knowing it) emotional malnutrition, the skin of the soul will fester with scurvy, the teeth of the heart will decay. Neither duration nor proclamation of commitment is necessarily the measure – there are ephemeral explosions of passion between strangers that make more erotic sense than many lengthy marriages, there are one-night stands in Jersey City more glorious than six-month affairs in Paris – but finally there is a commitment, however brief; a purity, however threatened; a vulnerability, however concealed; a generosity of spirit, however marbled with need; an honest caring, however singed by lust, that must be present if couplings are to be salubrious and not slow poison.