 In his historiographical studies, Harris gives considerable attention to Spinoza's and Hegel's metaphysics.By stressing the crucial relevance of Spinoza's doctrines of the infinity of the attribute of the "cogitatio", of the "idea ideae" and of the "intellectus infinitus dei" (the infinite mind of god) as an "infinite mode" of substance, Harris disputed what he saw as one-sided empiricist and materialistic interpretations of Spinoza's naturalism.He argues that Spinoza's polemic against the final causes ought to be understood as referring only to the standpoint of external teleology, and consequently that Spinoza does not exclude a valid explanation of natural processes in the light of an inner teleology.