Because I enjoyed being in the book’s world so much that I want to go back there, spend time with the characters (who wouldn’t want to talk to one of Pern’s dragons?).

Because the book has such an enthralling plot line that I raced through it and now I want to see what I missed (Alan Furst’s WW2 stories).

Because I couldn’t get into the book at first, so I skipped forward, then got hooked and read to the end; now I need to fill the gaps (true confession – that was how I read Captain Corelli’s Mandolin).

Because I didn’t understand it all the first time, and its subject or idea is something I want to know more about (popular economics books, textbooks, Lincoln in the Bardo…).

To see how the author does ‘it’: – and ‘it’ could be … hooks the reader (well this reader), or swaps point of view (Nora Roberts turns on a sixpence, or a paragraph – and carries the reader with her), or uses interior monologue (Sarah Moss), or lays down plot points without being obvious (Fred Vargas), or builds a world in a different time/place/reality from the one I live in (Madeleine Miller), or swaps time frames without confusion (and Maggie O’Farrell is a star practitioner).

So what about Hamnet? Shall I re-read it? I am re-reading it: recognising the home squeezed between the houses in Stratford, walking with Agnes to collect herbs, running with Hamnet to find help for his sister, and yearning to spend more time with William, hear him speak, read what he writes, learn how he thinks. Maggie O’Farrell’s creation slides seamlessly and convincingly, into the cracks between what I already know, of Shakespeare and his time, and what I surmise.

It is no plot-spoiler to say that the first half of the book is a tragedy, the author traces and describes the paths that lead the protagonists inevitably towards a death. But those routes are described in such detail that we readers accompany each character, feel their emotions, sense what they sense, inhabit their world.

In the second part of the book the surviving characters have to do just that – survive – despite, for some of them, crippling, mind-numbing grief. Knowing some of the historical record left me even more unsure than I might have been otherwise, about whether relationships and personalities, could ever recover. I found the end of the book deeply satisfying and (once again) convincing.

Deeply satisfying – but I find myself not sated, I’m rereading Hamnet.  And for which of the reasons listed above? Almost all of them – but chiefly the first.