From David Coomes' biography of Dorothy Sayers, A Careless Rage for Life, courtesy of the Repository Used Book Collection:
In a remarkable letter to Charles Williams in 1944, having got it into her head that Dante had been a passionate lover, [Dorothy Sayers] wrote of 'the distinguishing marks of True Bedworthiness in the Male', finding these 'to consist in the presence of Three Grand Assumptions':
1. That the primary aim and object of Bed is that a good time should be had by all.
2. That (other things being equal) it is the business of the male to make it so.
3. That he knows his business.
The first Assumption rules out at once all Satyromaniacs, sadists, connoisseurs in rape, egotists, and superstitious believers in female reluctance, as well as Catholic (replenish-the-earth) utilitarians and stockbreeders.
The second Assumption rules out the hasty, the clumsy, the lazy, the inconsiderate, the peremptory, the untimely and (in most cases) the routinier...
The third Assumption rules out the tentative as well as the incompetent and inadequate.