Hunger by Knut Hamsun (1890)

He pawns his waistcoat in the Kristiania winter to buy bread, then presses the coins into the hand of a beggar hungrier than himself, and the logic is airtight: a man may starve, but he will not let his pride be seen to bend. This is the engine of the whole book, an unnamed writer with nothing to sell but pages no editor wants, gnawing wood shavings to fool his stomach, his hair coming loose in his fingers, his mind racing toward the strange lucidity the starving sometimes know. Hamsun walked these streets before he wrote them, reaching for a form no one had named: a novel that follows not events but a feverish consciousness narrating its own ruin, one that cannot trust itself and cannot stop. There is almost no plot, only a mind held at the edge of collapse and watched in merciless close-up. You finish it having lived inside another person as completely as a book can let you.