A dead Deer
Two weeks ago when walking to shul on the morning of Rosh Hashanah I came across the carcass of a deer that had been killed by a car. Its ribs had already been picked clean by vultures (yes, we have vultures here in Maryland) and there was a mass of maggots covering the rear of the carcass. And by a mass I mean that it was not possible to see anything other than this swarm. The deer had been killed just a short time ago. The maggots appeared to have generated spontaneously.
The spontaneous generation of the half-mouse
In today's page of Talmud, we read about the mysterious mud mouse, a creature that is half flesh and half mud, that also appeared spontaneously.
סנהדרין צא, א
צא לבקעה וראה עכבר שהיום חציו בשר וחציו אדמה למחר השריץ ונעשה כלו בשר
Consider the mouse which today is half flesh and half earth, and tomorrow it has become a creeping thing made entirely of flesh.
Elsewhere, Rashi provides us with a detailed explanation about the creature that seems to raise more questions than answers:
רשי, חולין קכו, ב
יש מין עכבר שאינו פרה ורבה אלא מעצמו נוצר מאדמה כאשפה המשרצת תולעים
There is a species of mouse that does not reproduce sexually but is spontaneously generated from the earth, just as maggots appear at a garbage site.
Apparently, Rashi and the rabbis of the Talmud believed in spontaneous generation. Here is the opening of the Wiki article on the subject:
Spontaneous generation or anomalous generation is an obsolete body of thought on the ordinary formation of living organisms without descent from similar organisms. Typically, the idea was that certain forms such as fleas could arise from inanimate matter such as dust, or that maggots could arise from dead flesh.
Everyone Believed it
How could our esteemed rabbis believe in spontaneous generation? The answer is that everyone believed it, from the time of Aristotle until Louis Pasteur. Here is Aristotle (d. 322 BCE):
So with animals, some spring from parent animals according to their kind, whilst others grow spontaneously and not from kindred stock; and of these instances of spontaneous generation some come from putrefying earth or vegetable matter. [History of Animals 539a, 18-26.]
Spontaneous generation was an accepted theory throughout the middle ages and was found in the writings of Arab naturalists, such as Averroes. Sir Francis Bacon, (d.1626) the English "philosopher, statesman, scientist, jurist, orator, and author" accepted the theory. And so did Willam Harvey, who discovered the circulation of the blood, - at least under certain circumstances. And why not believe is spontaneous generation? Before the invention of the microscope, it certainly explained how worms, fleas and insects could appear out of no-where.
Then came the microscope. Using one, in October 1676, Leeuwenhoek reported finding tiny micro-organisms in lake water. Now perhaps there was another explanation for how things were created, although not much progress was made for a couple of hundred more years. It was Louis Pasteur (d.1895) who finally disproved the theory of spontaneous generation with some elegant experiments. He boiled a meat broth in a flask like this, with its neck pointed downwards.
Boiling sterilized the mixture, and with the neck pointing down, no organisms could contaminate the broth. As a result, there was no growth of bacteria or could inside the flask. He did the same using a flask with a neck that was upturned. This allowed the broth to become contaminated with organisms in the outside air, and the mixture soon became cloudy. Spontaneous generation had been disproven.
Where did those maggots come from?
After Rosh Hashanah ended I looked into the question of how those maggots could have appeared so quickly on the flesh of the dead deer. It turns out that the blowfly eggs are laid within minutes and hatch in a matter of hours. They did not appear spontaneously after all.
The history of science reminds us how to read the Talmud. Spontaneous generation was the way everyone assumed that some things were created. Whether you were a rabbi in the Talmud, a Greek philosopher, or an English scientist.