In the wake of the scientific advances of the eighteenth and nineteenth centuries, many attempted to reconcile science and religion. Few were as articulate as Drummond, who argues against the term "supernatural" but instead for the scientific idea of continuity, which he asserts extends to the spiritual realm. To the author, the spiritual is but a higher order of the natural—and therefore Darwin's theory of evolution can be wholly accepted and extended to affirm that the final step of evolution is the spiritual man.