On 5 February 1862, the night Abraham Lincoln and his wife gave a lavish reception in the White House, with the civil war swelling outside and their 11-year-old son Willie dying of typhoid fever upstairs, what was the state of the moon? Was it a ‘fat green crescent’? Or was it ‘yellow-red, as if reflecting the light of some earthly fire’?

According to George Saunders’s hugely ambitious Lincoln in the Bardo, his first novel after four peerless collections of short stories, neither of the above descriptions might be true, but when read in their tragic context, either can impart symbolic meaning....