Nor is this surprising, since he was ravaged by bodily complaints — piles, especially, and various forms of arthritis or rheumatism, described as "gout". He had periodic bouts of malaria, too, and seems to have suffered greatly from what we would have called common colds. In September 1553, after he had been obliged to abandon the siege of Metz, there was a pessimistic report on his health which Thomas quotes:

His Majesty cannot be expected to live long because of the great number of illnesses which affect him, especially inter...the gout attacks him and frequently racks all his limbs and nerves...[colds] affect him so much he sometimes appears to be in his last straits...his piles put him in such agony that he cannot move without great pain. 

There was also, the report goes on, "very great mental sufferings" so his "good humour and affability" have disappeared. Full of melancholy, he "would not allow anyone into his presence to deal with papers". All he wanted to do, "day and night", was to adjust and set "his countless clocks". He "does little else". 

Here, then, was the nemesis of power, and it is not surprising that Charles abdicated, the first ruler of his stature to do so since Diocletian. He seems to have got little pleasure from his rule of nearly half a century, though Thomas notes there were three or four illegitimate children, all girls. The incessant court entertainments over which he was obliged to preside must have seemed as big a burden as the endless travelling, camping, besieging and fighting. Charles, who was not without an active conscience, was also hag-ridden by moral problems. What to do about the reform of the Church? Should Protestants and other heretics be persecuted? Ought the Indians in Spanish territories to be actively Christianised? Was slavery, of Indians or Africans, permissible? No decisive answers were forthcoming to any of these questions. So the monastery to which Charles retired must have seemed welcoming. Not that he lived to enjoy it long (with an entourage of 50 secretaries and attendants, according to Thomas). Within two years his gout, or whatever it was, had killed him. Hugh Thomas, in describing the Golden Age of Spanish imperialism, has in fact written a morality tale about the futility of world power, and it is a convincing one.