Comment by Audrey Niffenegger, on The Guardian's website:

Time and Again is an original; there is nothing quite like it. It is the story of Si Morley, a commercial artist who is drawing a piece of soap one ordinary day in 1970 when a mysterious man from the US Army shows up at his Manhattan office to recruit him for a secret government project. The project turns out to involve time travel; the idea is that artists and other imaginative people can be trained (by self-hypnosis) to imagine themselves so completely in the past that they actually go there. Si finds himself sitting in an apartment in the famous Dakota building pretending to be in the past . . . and ends up in the Manhattan of 1882.

The story makes good use of paradox and the butterfly effect, but its greatest charms lie in Si's good-humoured observations of old New York and the love story that gradually develops between Si and the beautiful Julia, who doesn't believe Si when he tells her he's a time traveller. Time and Again is laden with authentic period photos and newspaper engravings which Jack Finney works into the narrative gracefully. When I first read WG Sebald's Austerlitz, a very different book in both subject and mood, I realised that it owed something to Finney's innovative use of pictures as evidence within a novel. Really, the pictures seem to say, this did happen, I saw it, don't you believe me? The pictures cause us, the readers, to sway slightly as we suspend our disbelief; they look like proof of something we know is unprovable. Isn't it?

There is something wistful about time travel stories as they age: 1970 is now 41 years past. A lot happened in those years, and these characters are blissfully unaware of the future. I get a little shiver of nostalgia in the book's opening pages: gee, people used to go to offices and sit at drawing boards and get paid to draw soap. What a world. Perhaps if I could imagine it completely enough, I could visit . . . but no. I'll just read about it, again and again.