 While the other two great rationalists, Descartes and Leibniz, were physical theorists and mathematicians of the first rank, who made substantial contributions to the development of physical science, the same cannot be said of Spinoza. Nor was Spinoza a systematic experimentalist. Indeed, his contributions to the historical development of physical theory are minimal. This is not because the physical theory he presented was rejected or overlooked, but rather because Spinoza simply never presented a physical theory as such. Most of his writing concerning physical theory is instead in the service of other ends: exegetical, as an expositor of Descartes' philosophy; metaphysical, in elaborating, for example, the relationships between God or Nature as the single substance and the finite things he treats as “modes” thereof; or psychological, in explaining the distinctive characteristics and possible blessedness of the human mind as the idea of an especially complex individual body.