During the course of Marxism's rise to prominence in the 1890s, two distinct groups of Marxists evolved away from orthodoxy: the "legal Marxists' and the "economists". Orthodoxy was defined by adherence to the tenets of Plekhanov's system, and the repudiation of any allegation that Marx's and Engels's work might be in need of correction or amendment, rather than merely being applied to new circumstances; its principal proponents were Plekhanov himself and Lenin. The "legal Marxists' included P. B. Struve, M. Tugan-Baranovsky and S. N. Bulgakov; Tugan-Baranovsky was by far the most important economic theorist. Their position prior to 1900 was to accept the political programme which Plekhanov had formulated, while adopting a critical perspective on the foundations of Marxian theory itself. At the turn of the twentieth century Struve, Bulgakov and other "legal Marxists' of lesser importance increasingly drifted away not only from Marxism, but also from materialism and socialism, embracing instead liberalism, idealism and moderation.¹