Other panpsychists of this time include Friedrich Paulsen (1846–1908), a student of Fechner’s who extended his teacher’s version of panpsychism, and Morton Prince (1854–1929), psychologist and physician who advocated a panpsychism that emphasized that it is matter that must be “psychologized” or imbued with mentalistic attributes (Prince regarded this as a form of materialism, and there are again affinities here with Russellian monism, discussed below). Also to be mentioned are Eduard von Hartmann (1842–1906) who extended his famous doctrine of the unconscious down to the level of atoms, Ferdinand C.S. Schiller (1864–1937) who provided a pragmatist defense of panpsychism as a doctrine which by various analogical arguments yields otherwise unattainable insights into nature, and Ernst Häckel (1834–1919), an early and avid proponent of Darwinism in Germany who interpreted our evolutionary connection with the rest of nature as evidence for panpsychism, and who was thus willing to ascribe mental properties to living cells.