The Book of Eels, Patrik Svensson [bill gates best books .TXT] 📗

at Plato’s feet in Athens for twenty years and in many respects came to be his equal. When Plato died and Aristotle was not appointed the new head of the Academy, he relocated to the island of Lesbos. It was there that he began to study animals and nature in earnest. Perhaps that was also where he first started thinking about how eels came to be.

Not much is known about Aristotle’s scientific method. He didn’t keep notes on his observations and dissections. He gave confident and detailed accounts of his discoveries and insights, but rarely said anything about how he had come to them. Nevertheless, we can be almost entirely certain that he personally performed many of the dissections that form the basis of Historia Animalium. Crucially, it seems clear he spent much of his time studying aquatic life-forms, and primarily the eel. If nothing else, his writings on what is hidden inside the eel, about the relative placement of its organs and the construction of its gills, are particularly copious and detailed.

Where the eel is concerned, he also often disagreed with other scientists whose names have been lost to posterity, as though the eel was already, at that time, a source of speculation, contradictory opinions, and conflict. Aristotle insisted categorically that eels never carry eggs in their bodies, declaring that anyone who claimed otherwise simply had not studied eels closely enough. There can be no doubt this is so, he wrote, because when you cut open an eel, not only will you not find eggs, you will also not find any organs for producing or transporting eggs or milt. Nothing about the eel’s existence explains how it is brought to life. He also stated that anyone claiming the eel gives birth to live young had been misled by his ignorance and that his opinions were not based on fact. Aristotle also made short shrift of those scientists who claimed eels could be sexed, pointing to the male head as being larger than that of the female. They had simply mistaken interspecies variation for sexual variation.

Aristotle had studied eels, that much is clear. Maybe on Lesbos, maybe in Athens. He had dissected them and studied their internal organs, had looked for eggs and reproductive organs and an explanation as to how they procreate. He had probably handled a great many eels, scrutinizing them, pondering what kind of creatures they were. And he had reached the conclusion that the eel is a thing unto itself.

The approach to understanding animals and nature developed by Aristotle would eventually come to shape—virtually single-handedly—both modern biology and the natural sciences, and thus all subsequent attempts to understand the eel. It was above all empirical. Nature can be described through systematic observation, Aristotle claimed, and only through correct description can it be understood.

It was a radical approach and, in every respect, a successful one. Many of Aristotle’s observations were surprisingly precise, not least considering they were made long before the field of zoology even existed as a concept. His knowledge was way ahead of his time, particularly when it came to aquatic species. He explained and described, for example, the anatomy and reproduction of octopuses in a way that modern zoology was able to verify only in the nineteenth century. And with regards to the eel, Aristotle claimed, correctly, that it can move between freshwater and saltwater, that it has unusually small gills, and that it is nocturnal, hiding in deeper water during the day.

But the eel was also a subject about which Aristotle made an unusual number of obviously outlandish claims. Despite his systematic method based on observation, he never did manage to understand the eel. He wrote that eels eat grass and roots and sometimes even mud. He wrote that it has no scales. He wrote that it lives for seven or eight years and that it can survive for five or six days on land and even longer if the wind blows from the north. And, as already mentioned, he asserted that eels do not have biological sex and that they are created from nothing. The first embodiment of the eel, Aristotle concluded, is in fact a small maggot-like creature, a kind of earthworm that is spontaneously and without the involvement of any other living thing generated from mud. This worm can spring to life in both seas and rivers, especially where there is plenty of decomposing vegetation, and it prefers shallow marshes or beds of seaweed where the sun warms the water. “There can be no doubt about this being so,” Aristotle writes, and then wraps up his discussion. “Enough about the reproduction of the eel.”

ALL KNOWLEDGE COMES FROM EXPERIENCE. THAT WAS ARISTOTLE’S first and most fundamental insight. Any study of life must be empirical and systematic. Reality must be described as it is perceived by our senses. First, one establishes that something is; then one can focus on the question of what it is. And only when one has collected all the facts about what something is, is it possible to approach the metaphysical question of why it is the way it is. That is also the insight that has served as the basis for most attempts to gain a scientific understanding of the world since Aristotle’s time.

But why is it that the eel was able to slither out of Aristotle’s grasp? That is the question that seems impossible to answer. No matter how meticulously and systematically he studied the eel, he reached conclusions that now appear almost absurdly unscientific. And that’s what makes the eel unique. Science has come up against many mysteries, but few have proven as intractable and difficult to solve as the eel. Eels have turned out to be not only uncommonly difficult to observe—due to their strange life cycle, their shyness, their metamorphoses, and their roundabout approach to reproduction—but also secretive in a way that comes across as deliberate and preordained. Even when successful observation is possible, even when you get really close, the eel seems