Calmet, the well-known Benedictine Abbot of Senon, in Lorraine, who was one of the most renowned theological writers of the eighteenth century, says (i. 17): "Apparitions of ghosts would be more readily understood if spirits had a body; but the Holy Church has decided that angels, devils and the spirits of the departed are pure immaterial spirits. Since this question transcends our mental faculties, we must submit to the judgment of the Church, which cannot err." Another great theologian, the German Bengel, on the contrary, assumed that "probably the apparitions of the departed have a prescribed limit and then cease; they continue probably as long as all the ties between body and soul are not fully dissolved." This question of the nature of our existence during the time immediately following death, is, it is well known, one of the most vexed of our day, for while most divines of the Protestant Church assume an immediate decision of our eternal fate, others admit the probability of an intermediate state, and the Catholic Church has its well-known probationary state in purgatory. It may as well be stated here at once that the whole theory of ghosts is admissible only if we assume that there follows after death a period during which the soul undergoes, not an immediate rupture, but a slow, gradual separation from its body, accompanied by a similar gradual adaptation to its new mode of existence. Whether the spirit, during this time, is still sufficiently akin to earthy substances to be able to clothe itself into some material perceptible to the senses of living men, is of comparatively little importance. The idea of such an "ethereal body" is very old, and has never ceased to be entertained. Thus, in 1306, already Guido de la Tones, who died in Verona, appeared during eight days to his wife, his neighbors, and a number of devout priests, and declared in answer to their questions that the spirits of the departed possessed the power to clothe themselves with air, and thus to become perceptible to living beings. Bayle also, in his article on Spinoza (note 2), advocates the possibility, at least, of physical effects being produced by agents whose presence we are not able to perceive by the use of our ordinary senses. Even so eminently practical a mind as Lessing's was bewildered by the difficulties surrounding this question, and he declared that "here his wits were at an end."