transformation defies any attempts to explain

I'm almost done with this book and I'm enjoying it very much - so much that I'm in no hurry to finish because then it will be over. Half of the story takes place in Italy in the early 60s vaguely around the filming of Cleopatra, half takes place in present day Hollywood(ish). Usually when there's this kind of divide I prefer one setting over the other, but in this book it's so well balanced I'm happy to return to any set of characters.

Here's a quote from p. 93, describing Michael Deane ("the Deane of Hollywood"), now an old man struggling for relevance in the current business.

Suffice it to say that, upon meeting Michael for the first time, many people stare open-mouthed, unable to look away from his glistening, vaguely lifelike face. Sometimes they cock their heads to get a better angle, and Michael mistakes their morbid fascination for attraction, or respect, or surprise that someone his age could look this good, and it is this basic misunderstanding that causes him to be ever more aggressive about fighting the aging process. It's not just that he gets younger-looking each year, that's common enough here; it's as if he is somehow transforming himself, evolving into a different being altogether, and this transformation defies any attempts to explain it. Trying to picture what Michael Deane looked like as a young man in Italy fifty years ago, based on his appearance now, is like standing on Wall Street trying to understand the topography of Manhattan Island before the Dutch arrived.