Toward the beginning of the eighteenth century, soul theorists were still anxious to defend the immaterial substantiality of the soul against those who would account for self and personal identity along relational lines. They had not yet felt the winds of history blowing against them. As the century wore on, the winds eventually became a gale. Soul theorists could not help but notice. One effect of their noticing had to do with their willingness to defend the view that the soul is immaterial. Clarke’s bravado contrasts nicely with the defensiveness of Berkeley and Butler, and, with the subsequent reluctance of soul theorists, after Hume, even to do battle on the issue. Another effect is that for soul theorists, toward the beginning of the century, it was enough simply to defend the immateriality of the soul and related a priori doctrines, such as the reflexivity of consciousness, without also contributing to the emerging science of human nature. Again, Clarke is the premier example. Later in the century, many soul theorists bracketed their commitment to the immateriality of the soul in order to conduct meaningful empirical research.