Buchner: Experience and daily occupation teach us that the spirit perishes with the material substratum--that man dies. ("Matter and Force.") Burmeister: That the soul of a deceased person does not re-appear after death, is not contested by rational people. Spirits and ghosts are only seen by diseased or superstitious individuals. Vogt: Physiology decides definitely and categorically against individual immortality, as against any special existence of the soul. The soul does not enter the foetus like the evil spirit into persons possessed, but is a product of the development of the brain, just as muscular activity is a product of muscular development. So soon as the substances composing the brain are aggregated in a similar form, will they exhibit the same functions. We have seen that we can destroy mental activity by injuring the brain. By observing the development of the child we also arrive at the conviction that the activity of the soul progresses in proportion as the brain is gradually developed. The foetus manifests no mental activity, which only shows itself after birth when the brain acquires the necessary material condition. Mental activity changes with the period of life, and ceases altogether at death. Lecky: ("Rat. in Europe," p. 341, v. I.) Not one of the early fathers entertained the same opinion as the majority of Christians do of the present day, that the soul is perfectly simple, and entirely destitute of all body, figure, form, and extension. On the contrary, they all acknowledged it to contain something corporeal, although of a different kind and nature from the bodies of this mortal sphere.... Tertullian mentions a woman who had seen a soul, which she described as "a transparent and lucid figure, in the perfect form of a man." St. Anthony saw the soul of Ammon carried up to heaven. The soul of a Libyan hermit named Marc was borne to heaven in a napkin. Angels also were not unfrequently seen, and were universally believed to have cohabited with the daughters of the antediluvians.... Sometimes the soul was portrayed as a sexless child, rising out of the mouth of the corpse. John Meslier: ("Testimony of a Dying Priest.") The barbarians, like all ignorant men, attribute to spirits all the effects of which their inexperience prevents them from discovering the true causes. Ask a barbarian what causes your watch to move, he will answer, "A spirit." Ask our philosophers what moves the universe, they will tell you, "It is a spirit." Ask a theologian what he means by a spirit. He will answer that it is an unknown substance, which is perfectly simple, which has nothing tangible, nothing in common with matter. In good faith, is there any mortal who can form the least idea of such a substance.