The State and Revolution is considered to be Lenin's most important work on the state and has been called by Lucio Colletti "Lenin's greatest contribution to the political theory". According to the Marxologist David McLellan, "the book had its origin in Lenin's argument with Bukharin in the summer of 1916 over the existence of the state after a proletarian revolution. Bukharin had emphasized the 'withering' aspect, whereas Lenin insisted on the necessity of the state machinery to expropriate the expropriators. In fact, it was Lenin who changed his mind, and many of the ideas of State and Revolution, composed in the summer of 1917 - particularly the anti-Statist theme - were those of Bukharin".