 In the generation immediately preceding Whitehead, C. S. Peirce (1839–1914) and William James (1842–1910) closely anticipated process theism and served as important influences on its development. There was also a cross fertilization of ideas from some of Whitehead’s contemporaries: Henri Bergson (1859–1941), Samuel Alexander (1859–1938), and William Ernest Hocking (1873–1966)—Hocking was one of Hartshorne’s teachers at Harvard. Philosophers and religious thinkers who independently formulated aspects of process theism in the twentieth century include: Bernardino Varisco (1850–1933), Nicholas Berdyaev (1874–1948), Mohammad Iqbal (1877–1938), Martin Buber (1878–1965), Pierre Teilhard de Chardin (1881–1955), Edgar Sheffield Brightman (1884–1953), Sarvepalli Radhakrishnan (1888–1975), Sri Aurobindo (1892–1950), Hans Jonas (1903–1993), and Abraham Joshua Heschel (1907–1972).