Later he enrolled in the University of Helsinki as a theology student, according to his uncle Toivo's wishes, but soon abandoned theology in favour of philosophy, aesthetics and literature, graduating in 1929. While studying, he contributed to various magazines and wrote poetry and stories, getting his first book "Jumalaa paossa" published in 1925 - it was a success, selling 3000 copies despite being only 72 pages long. In 1927 he went to Paris where he wrote his first major novel "Suuri illusioni" ('The Grand Illusion'), a story of bohemian life. In terms of style, the novel is considered to be the Finnish equivalent to the works of the American writers of the Lost Generation. (In Waltari's historical novel "The Adventurer", taking place in the 16th century, the protagonist is a Finn who goes to study in Paris at much the same age that the author went to the same city in the 20th century). "Suuri Illusioni" was a surprise hit, selling 8000 copies and turning Mika Waltari into a famous author. Waltari also was, for a while, a member of the liberal literary movement Tulenkantajat, though his political and social views later turned conservative. He was married on 8 March 1931 to Marjatta Luukkonen, whom he had met during military service the preceding year, and on 4 January 1932 they had a daughter, Satu. Satu also became a writer.