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O Livro de Mórmon/Anacronismos/Suor e poros da pele
Question: Is the Book of Mormon reference to blood coming from Christ's pores anachronistic?
The Book of Mormon mentions skin pores
The Book of Mormon contains a reference to the intense agony endured by Jesus Christ as he atoned for the sins of all humanity:
And lo, he shall suffer temptations, and pain of body, hunger, thirst, and fatigue, even more than man can suffer, except it be unto death; for behold, blood cometh from every pore, so great shall be his anguish for the wickedness and the abominations of his people. (Mosiah 3:7, emphasis added.)
Since the Nephite authors would not have known about skin pores, is the reference to skin pores anachronistic?
The concept of having pores in the skin through which sweats, fluids, or gases could pass is of great antiquity
The concept of having pores in the skin through which sweats, fluids, or gases could pass is of great antiquity. Pores and the associated sweat gland apparatus were not demonstrated microscopically until 6 years after the publication of the Book of Mormon.
Latter-day Saints regard the Atonement of Christ, during which he suffered incomprehensible and unbearable agonies, as the most important event in human history. While the technical details of that experience are of minor importance, the Book of Mormon's account is consistent with ancient medical and anatomical concepts, and well-documented case reports from the modern era.
However, rather than focus on microscopy or physiology, members of the Church hope to spend far more time obeying Jesus' command to repent, which he gave in a description of the atonement as revealed to Joseph Smith:
- 15 Therefore I command you to repent—repent, lest I smite you by the rod of my mouth, and by my wrath, and by my anger, and your sufferings be sore—how sore you know not, how exquisite you know not, yea, how hard to bear you know not.
- 16 For behold, I, God, have suffered these things for all, that they might not suffer if they would repent;
- 17 But if they would not repent they must suffer even as I;
- 18 Which suffering caused myself, even God, the greatest of all, to tremble because of pain, and to bleed at every pore, and to suffer both body and spirit—and would that I might not drink the bitter cup, and shrink—
- 19 Nevertheless, glory be to the Father, and I partook and finished my preparations unto the children of men.
- 20 Wherefore, I command you again to repent, lest I humble you with my almighty power; and that you confess your sins, lest you suffer these punishments of which I have spoken, of which in the smallest, yea, even in the least degree you have tasted at the time I withdrew my Spirit. (D&C 19:15–20.)
Question: When were skin pores discovered?
Although pores couldn't be seen, they were speculated about anciently.
Contrary to the critics' assertion, the medicine of antiquity had long speculated and written about "pores."
- Empedocles, a Greek philosopher who lived from about 490–430 B.C., believed that air and vapour could pass into or out of the body via pores. 
- Galen, the Greek physician of the Roman era (A.D. 129–c. 210) likewise believed that "innnumerable skin pores" drew air into the body, and also expelled wastes.  Galen was of multiple opinions on sweat (Gk ιδρος=hidros), but he sometimes claimed that it leaked out from skin pores in droplet form. 
- A variety of other classical physicians (such as Ascelepiades, Petronas, Soranus, Themison) believed that tightening of the pores was a potential cause of disease, and a variety of regimens were recommended to overcome this (e.g. purging, hot baths and drinks, heavy bedclothes to cause sweats, induced vomiting). 
- John of Gaddesdon (c.1280–1349?1361) was physician to the Royal Household in England during the 14th century, and the first English author of a published medical book.  He wrote of a disease that:
- The cause of it is in the grossness of the matter of the body or the blocking up of the pores from an external cause ... the heat of the sun or a fire, or from cold water; briefly anything that closes the pores and prevents the escape of vapours. 
- French physician Ambroise Paré (1510–1590) wrote in 1554 that the skin "is penetrated by many pores or breathing places, as we may see by the flowing out of sweat." 
Despite at least two millenia of theory and discussion in the medicine of antiquity, the skin's pores had not been seen! English anatomist William Cumberland Cruikshank (1745-1800) indicated that "after some pains, and assisted with a pretty good microscope, I have not been able to discover perforations in the cuticle or rete mucosum [i.e. pores in the skin].... I believe, nevertheless, that they certainly exist." 
Question: What did those in Joseph Smith's day know about sweat and pores?
Those in Joseph Smith's day did not know much more about sweat and pores than classical writers of 2500 years earlier did.
American medicine at the time of Joseph Smith was still exceedingly primitive. Medical practitioners still drew heavily on the theories and works of antiquity for medical theory, diagnosis, and treatment.
As discussed above, the concept of "pores" in the skin for sweat and other substances is an ancient one in western medicine. Despite this, the pores had never been definitively demonstrated throughout the skin.
A popular medical textbook of the time, Buchan's Domestic Medicine Modernized, etc. (1807) blamed the following diseases on blocked perspiration: most fevers, gout, rheumatism, scurvy, asthma, epilepsy, hypochondria, and inflammation of lung, kidney, bowel, and brain. 
Thus, contrary to the critics' claims, Joseph Smith or his contemporaries were no better suited to know the facts about skin pores or sweat than classical writers of 2500 years earlier. Theory and knowledge on the subject had not advanced much, and a rural farmboy such as Joseph would hardly have been aware of any of the learned discussions taking place on the topic, which were not terribly advanced anyway.
Sweat glands and associated structures were finally demonstrated to exist in 1835, six years after the translation of the Book of Mormon.  The modern understanding of sweat and the role of the skin in fluid homeostasis was fixed around the turn of the century. 
Joseph Smith had as much chance at being right about the relationship between sweat and pores as an ancient author writing thousands of years earlier.
Question: Can skin pores produce blood?
Although rare, the excretion of blood through pores has been known to occur.
Critics of Christianity generally have sometimes questioned Luke's account of Christ sweating "drops of blood."
But, the phenomenon of "hemohidrosis" or "hematidrosis" (blood in the sweat), while rare, is certainly known from both historical and modern accounts.
An epidemic disease (called the sweating sickness) in England between 1485 and 1581 caused "bloody sweat." Suggested causes have included hantavirus,  relapsing fever (a tick-borne disease), or anthrax.  Influenza has also been considered, but recent reviewers remain unconvinced. 
A Chinese study reported a case of bloody sweat which described a patient in which "episodes of skin bleeding occurred on any site of the body spontaneously and promptly." The blood was identical to blood drawn from the patient's circulatory system, and the sweat glands were normal. It was hypothesized that this case was the result of a vasculitis (inflammation of blood vessels) which allowed the leak of blood. 
Another review of the literature found that the causes of modern cases of "bloody sweat" have included:
- other systemic disease
- excessive exertion
- psychologic distress
- unknown 
Thus, it seems clear that severe mental and/or physical anguish can cause this condition, just as reported by the Book of Mormon and the gospel of Luke.
- E.T. Renbourn, "The Natural History of Insensible Transpiration: A Forgotten Doctrine of Health and Disease," Medical History 4/2 (April 1960): 135. off-site
- Renbourn, 135–136.
- Renbourn, 136.
- Renbourn, 136–137.
- "John of Gaddesden's Rosa Anglica," King's College London off-site
- John of Gaddesden, Rosa Anglica practica medicine a capita ad pedes (Pavia: Joanes-Antonius Birreta, 1492); translation and cited by Renbourn, 137.
- Ambrose Paré, Works (1554); Trans. from Latine by J. Johnston, 1664; cited by Renbourn, 137.
- W.C. Cruikshank, Experiments on the Insensible Perspiration of Huamn Bodies, etc. (1785); cited by Renbourn, 146.
- Renbourn, 147–148.
- Renbourn, 149.
- Renbourn, 150.
- Eric Bridson, "The English 'sweate' (Sudor Anglicus) and Hantavirus pulmonary syndrome," British Journal of Biomedical Science 58/1 (1 January 2001): 1–6; first published in Medical Sciences History 14 (1998): 20–32. off-site
- E McSweegan, "Anthrax and the etiology of the English sweating sickness," Medical Hypotheses 62/1 (1 Jan 2004): 155–7. off-site
- Burke A. Cunha, "Influenza: historical aspects of epidemics and pandemics," Infectious Disease Clinics of North America 18/1 (March 2004): 141–155. off-site
- FK Zhang, Zhonghua Xue Ye Xue Za Zhi ("Clinical and laboratory study of a case of hematidrosis") in Chung-Hua Hsueh Yeh Hsueh Tsa Chih ¦ (Chinese Journal of Hematology) 25(3) (01 March 2004): 147–50. off-site
- JE Holoubek, "Blood Sweat and Fear: A classification of hematidrosis," Journal of Medicine 27/3–4 (1 Jan 2006): 115–133. off-site