Despite the terminal state of his health, Clive James has been reading as if there is no tomorrow, which soon, he acknowledges, will be the case. In the introduction to his new book, Latest Readings (Yale, £12.99), a series of short essays mostly devoted to books he has been revisiting, he writes: "If you don't know the exact moment when the lights will go out, you might as well read until they do." It should be his family motto.

So widely and well has he been reading since his illness, few could match him, yet there is nothing boastful about James's insatiable consumption. Like the addict he is, he's almost shamefaced about his need for books, as when writing of the thousands he had to sell in order to relocate permanently to Cambridge, and his incurable mania for buying more to fill the gaps. Describing the spillage from other rooms into his inner sanctum, a tide that includes the Flashman adventures, which he has never read, he sighs: "Now that they have invaded my kitchen, they must be dealt with." You can be fairly sure that scarcely had that sentence been written than he had made the bully and cad's acquaintance, and would not end the relationship until the series had been read, first to last.

For the most part, though, James is doing what many readers do when in search of solace: turning back to authors they have especially enjoyed or admired. These include Hemingway, Anthony Powell, Evelyn Waugh and Philip Larkin. Foremost, though, is Conrad, whose novels have been the spine of this exercise, forcing him to reread the lot, one after the other, as if he were spooning up soup before it gets cold, even though he would have preferred to space them out.

His observations on individual books are acute and sometimes challenging, although one would like to challenge him in turn for some of his conclusions, as when he cavalierly dismisses Laurence Durrell's Alexandria Quartet as "a whole platter of overripe fruit". But there can be no better description of Powell's A Dance to the Music of Time than when he says that one of its chief pleasures is, "to read, while travelling in a second-class carriage, about the kind of people who used to travel in first".

Rereading is an under-rated art in a time where the new is exalted, and the future promises always to be brighter than the present or the past. To return to an author first read many years earlier is as much an act of memory and memoir as of literary appreciation, though the two are indivisible. James brings a rigorously analytical mind to his evaluations, and is usually if not always persuasive. Few of us are as intellectually gifted, but even if one's critical faculties are not as brilliant, the experience of rediscovering an old favourite, and finding it either better, or less good than before, is both stimulating and melancholy, no matter the depth of our understanding. There are some books I doubt I will ever reread, for fear of disillusionment; others that are neglected because it is too painful to remember the people or events they are associated with. And some that I am so guilty at having left half-read, I cannot bring myself to start again, as if the book might reproach me at every page.

There can be few greater satisfactions in the reading life, though, than going back to a book that made an enduring impression, and finding it even richer than you first thought. For many of the finest works, this is inevitably the case, and a second reading, even a third, is simply not enough. Few avid readers become worse readers, and most become more accomplished and aware. We are perhaps less in a rush for sensation, and more willing to enjoy the unfolding, be it in Henry James's puritanically unhurried manner, or Hemingway's bullish attack. Thus, those shelves of dog-eared works, last read a decade or three ago, are literary gold. Unlike the rows of new, untried books, they need no panhandler.