Who was Joseph Kohler and why he was against materialistic legal interpretation?

Joseph Kohler was a disciple of Hegal, who vehemently protests materialistic legal interpretation. He says, a unity of spirit rules mankind and evolutionary forces its way out of universal substances. Materialism is dead, the philosophy of spirit lives’ further, he says mankind constantly progress in culture in the sense that permanent cultural values are produced and law becomes a means to serve and advance cultural values. Kohler agrees with Stammler’s natural law with variable content.