Weber began his studies of the subject in The Protestant Ethic and the Spirit of Capitalism, in which he argued that the redefinition of the connection between work and piety in Protestantism and especially in ascetic Protestant denominations, particularly Calvinism, shifted human effort towards rational efforts aimed at achieving economic gain.[12][13] In the Protestant religion, piety towards God was expressed through one's secular vocation (secularisation of calling).[13] The rational roots of this doctrine, he argued, soon grew incompatible with and larger than the religious and so the latter were eventually discarded.[14]