“Nostalgia,” Agnes Arnold-Forster tells us – echoing a graffito reported near the refectory at Middlesex Polytechnic in 1974 – “isn’t what it used to be.” From “the Swiss Alps in the 17th century... to the election campaigns of Donald Trump”, she traces startling transmogrifications in her story of how scientists, scholars and self-interested manipulators have used and abused the word.