Any Human Heart: The Intimate Journals of Logan Mountstuart is a 2002 novel by William Boyd, a British writer. It is written as a lifelong series of journals kept by the fictional character Mountstuart, a writer whose life (1906–1991) spanned the defining episodes of the 20th century, crossed several continents and included a convoluted sequence of relationships and literary endeavours. Boyd uses the diary form to explore how public events impinge on individual consciousness, so that Mountstuart's journal alludes almost casually to the war, the death of a prime minister or the abdication of the king. Boyd plays ironically on the theme of literary celebrity, introducing his protagonist to several real writers who are included as characters.