Thus, Kashmir Shaivism is also propounding of theistic monism or panentheism. Marx credited the Scottish Enlightenment writers for originally propounding a materialist interpretation of history. The Sikh Gurus undoubtedly were very important in propounding the tenets of Sikhism. Upon retiring to England in 1868, Lewins turned his attention to propounding his atheist philosophy. He gave frequent public lectures throughout the country propounding his ideas. Laplace also came close to propounding the concept of the black hole. Stoddard is credited with propounding the "Half-way Covenant", at Northampton on 18 April 1661.