...whereas the vices of Messalina were in themselves venial, being mostly a passion for sensual gratification which subordinated all things to its encompassing, Agrippina lived solely for power, frightening enough in a man but terrifying in a woman....she would sleep with anyone, though not for physical pleasure, only for political advantage. She was cursed or blessed with a certain sexual coldness, knowing as much as a temple prostitute about the arousing of male passion and the procurement of its ecstatic release but keeping herself aloof, despite an occasional simulation of desire and the odd false orgiastic shudder and scream of fulfilment, from a process she found distressingly bestial when it was not frankly comic.
Anthony Burgess