Tolstoy cites the time, effort, public funds, and public respect spent on art and artists as well as the imprecision of general opinions on art as reason for writing the book. In his words, "it is difficult to say what is meant by art, and especially what is good, useful art, art for the sake of which we might condone such sacrifices as are being offered at its shrine".

Throughout the book Tolstoy demonstrates an "unremitting moralism", evaluating artworks in light of his radical Christian ethics, and displaying a willingness to dismiss accepted masters, including Wagner, Shakespeare, and Dante, as well as the bulk of his own writings.

Having rejected the use of beauty in definitions of art (see aesthetic theory), Tolstoy conceptualises art as anything that communicates emotion: "Art begins when a man, with the purpose of communicating to other people a feeling he once experienced, calls it up again within himself and expresses it by certain external signs".

This view of art is inclusive: "jokes", "home decoration", and "church services" may all be considered art as long as they convey feeling. It is also amoral: "[f]eelings … very bad and very good, if only they infect the reader … constitute the subject of art".

Tolstoy also notes that the "sincerity" of the artist—that is, the extent to which the artist "experiences the feeling he conveys"—influences the infection.

What is Art? (Russian: Что такое искусство? Chto takoye iskusstvo?) is a book by Leo Tolstoy. It was completed in Russian in 1897 but first published in the English due to difficulties with the Russian censors.

Lev Nikolayevich Tolstoy (Russian: Лев Никола́евич Толсто́й; 9 September [O.S. 28 August] 1828 – 20 November [O.S. 7 November] 1910), also known as Leo Tolstoy, was a Russian novelist, short story writer, essayist, playwright and philosopher who primarily wrote novels and short stories. Tolstoy was a master of realistic fiction and is widely considered one of the greatest novelists of all time. He is best known for two long novels, War and Peace (1869) and Anna Karenina (1877). Tolstoy first achieved literary acclaim in his 20s with his semi-autobiographical trilogy of novels, Childhood, Boyhood, and Youth (1852–1856) and Sevastopol Sketches (1855), based on his experiences in the Crimean War. His fiction output also includes two additional novels, dozens of short stories, and several famous novellas, including The Death of Ivan Ilyich, Family Happiness, and Hadji Murad. In addition to novels and short stories, he also wrote plays and philosophical essays on Christianity, nonviolent resistance, art and pacifism.

Tolstoy is equally known for his complicated and paradoxical persona and for his extreme moralistic and ascetic views, which he adopted after a moral crisis and spiritual awakening in the 1870s, after which he also became noted as a moral thinker, social reformer, and Georgist. His literal interpretation of the ethical teachings of Jesus, centering on the Sermon on the Mount, caused him in later life to become a fervent Christian anarchist and anarcho-pacifist. His ideas on nonviolent resistance, expressed in such works as The Kingdom of God Is Within You, were to have a profound impact on such pivotal twentieth-century figures as Mohandas Gandhi, Martin Luther King, Jr., and James Bevel.