From Peter Ackroyd's Life of Thomas More

"Some years later [Thomas More] advised Thomas Cromwell that, in serving the king, 'ever tell him what he ought to do but never what he is able to do...For if a lion knew his own strength, hard were it for any man to rule him.'  This is similar to the recommendation given by Thomas Wolsey to another royal servant:  'I warn you to be well advised and assured what matter ye put in his head; for ye shall never pull it out again.'  Wolsey, too, dwells upon the cupidity of the king--'rather than he will either miss or want any part of his will or appetite, he will put the loss of one half of his realm in danger.'  Both men spoke of a man whom they knew intimately, but perhaps even they could not have guessed the carnage and destruction which would follow their own deaths."