Chazal, Galen and Nishtaneh haTeva

The concept of nishtaneh hatevah - that the nature of physical reality has changed (see Tosafot, Moed Katan 11a) - is commonly proposed by the most extreme OrthoFundies as a last resort when they cannot reconcile the current state of scientific knowledge with statements of chazal. This idea can encompass the range of everything from a relatively reasonable assertion (although still without any scientific evidence) such as a purely morphological change (cannot jive the shiur of a k'beitzah or a k'zayit with the size of an egg or olive? The size of eggs and olives have gotten (much) smaller in the last 2000 years!) to the wackiest claims of relating to astronomical phenomena (geocentrism, spheres around the earth). Lice reproduce via spontaneous generation (so that we can kill them on Shabbat)? Well they must have done so 1500 years ago when the Talmud was written down! A seven month old fetus is more viable than an eighth month fetus? Eating fish and meat together are a danger? Can't rely on the medical cures of the Talmud any longer? Nishtaneh hatevah.

But my purpose here is not to beat a dead horse. You've seen many postings over the years discussing the absurdity of such a notion, and are well aware that Rabbi Natan Slifkin's books were banned by some gedolim - in part - for suggesting that chazal relied on the science of the time and were thus often wrong in their beliefs regarding the nature of physical reality, a notion anathema to some folks.

I recently came across a fascinating parallel idea taken from the annals of the history of medicine, as described in Bill Schutt's book, Dark Banquet: Blood and the Curious Lives of Blood-Feeding Creatures. (Warning: don't read if the nitty gritty details about bed bugs creep you out!)

The medical theories of Roman physician, Galen of Pergamum (CE 129 – 200, contemporaneous with Rabbi Yehudah haNasi, the redactor of the Mishnah) dominated Western medical science for more than 1300 years. Although he proved that “blood, not pneuma (an airlike spiritual essence dreamed up by the ancient Greeks), traveled through arteries”, he also “had no real concept of blood circulation. He believed that blood ebbed and flowed like the tides, with venous blood originating from and returning to the liver… Galen's deeply flawed concepts of human anatomy and physiology would have a serious and long-lasting effect on the field of medicine— especially with regard to the circulatory system. As previously mentioned, Galen's overarching ideas on the human body were generally extensions of those proposed by the ancient Greeks, and these mistake-laden views came to completely dominate the field of medicine. Not only did Galen's take on medicine and anatomy remain pervasive for fifteen hundred years, it remained unchallenged. According to Bill Hayes, the author of Five Quarts—A Personal and Natural History of Blood, "In the early Middle Ages, church leaders declared his work to have been divinely inspired and thus infallible." Rather than experimenting or dissecting specimens (and thereby bringing down upon themselves the serious and often deadly wrath of the church), the disciples of "Galen the Divine" simply deferred to their long-deceased master and his stance on any given medical topic. Anything else would have been blasphemous…”

“One of those responsible for attempting to revive experimental medicine was Andreas Vesalius. Born into a family of Belgian physicians, Vesalius received his doctorate in 1537 from the University of Padua, where he soon became the chair of surgery and anatomy… Rather than blindly accepting Galen's well-worn teachings, Vesalius took a new and dangerous approach. He employed dissection in his classroom and preached a hands-on approach to his students… The young anatomist not only studied their anatomy but also produced a set of remarkable and highly detailed anatomical diagrams, which were included in his seven-volume On the Fabric of the Human Body. It was his master-work and it hammered Galen's inaccurate and erroneous views on anatomy into the ground like so many tent pegs. Using cadavers, Vesalius disproved Galen's concept of invisible pores in the heart. He also demonstrated that the human heart had four chambers (not three) and that half of the body's major blood vessels did not originate in the liver (as described by Galen)...”

“Understandably, Vesalius (who was not yet thirty) upset many of the Galen faithful by dismantling so many of their master's long-held claims. One outraged Galenite went so far as to publish a paper in which he asserted that the work of Vesalius didn't prove Galen wrong, it simply indicated that the human body had changed since Galen's time.”