Felicitas Goodman, in her study of spirit possession, goes a step further, assum - ing a decidedly agnostic stance toward the existence of the spirits reported by her subjects. The experience of [the] presence [of spirits] during possession is accompanied by observable physical changes. We should remember that whether these changes are internally generated or created by external agencies is not discoverable. No one can either prove or disprove that the obvious changes of the brain map in possession or in a patient with a multiple personality disorder, for that matter, are produced by psy - chological processes or by an invading alien being (Goodman, 1988, p. 126). Goodman’s agnosticism is but a small step away from John Mack’s qualified acceptance of the existence of alien abductors