The Medusa and the Snail

President of Memorial Sloan-Kettering Cancer Center in New York City, Dr. Lewis Thomas’s collection of twenty-nine brief essays, The Medusa and the Snail (1974), is a follow up to The Lives of a Cell, winner of the 1974 National Book Award. The essays explore everything from the science of medicine to the philosophies of Montaigne, often reinforcing the symbiotic relationships between man and nature, as well as the self and the other. The title essay refers to a mature jellyfish (medusa) that happily envelops a tiny sea slug (snail), but over time, is slowly devoured by the slug until it becomes a parasitic appendage. This serves as a therapeutic metaphor for dealing with one’s imminent mortality. Additional essay topics include selfhood, human cloning, disease, natural death, warts, etymology, health care, modern medicine, and more.

In the opening essay, The Medusa and the Snail, Thomas details a mutually symbiotic relationship between a mature jellyfish (the Medusa) and a tiny sea slug (the Snail). As the two organisms start off happily functioning together in the Bay of Naples, Thomas describes a slowly evolving relationship that alters the symbiosis. First, he makes the link between the self and the other by demonstrating how the slug and jellyfish find each other. The jellyfish, located on the ventral surface of the slug, proactively engulfs the slug, forming a beneficial bond between both entities. Over time, however, the slug slowly devours the jellyfish, bit by bit, until the jellyfish dwindles into a “successfully edited parasite” attached to the skin surrounding the slug’s mouth. Thomas details how a “mix-up of selfness” evolves from a mutually beneficial symbiosis to a parasitic symbiosis, altering the health of both organisms along the way. He uses this metaphor for the uniqueness of nature that is shared across macro and microorganisms.

In “To Err is Human,” Thomas emphasizes the importance of trial by error as a means of making progress. In a thesis that recurs throughout his essays, he stresses how the ability to make mistakes is essential for an organism to evolve. After a trip to The Tucson Zoo in Arizona, Thomas questions whether his “coded” behavior when faced with certain stimuli is actually beneficial or not. He wonders if selflessness, a primitive human characteristic often attributed as ethically noble, is actually a sign of weakness rather than strength. Thomas continues the discussion of the moral, ethical self, framing it on the controversy of human cloning. In his view, cloning not only robs one of one’s self, it inevitably leads to becoming an “absolute, desolate orphan.” In “The Wonderful Mistake,” Thomas insists that the mistakes afforded to humans allow for growth, adding, “The capacity to blunder is the real marvel of DNA.” As such, Thomas argues that mistakes ought to be built into manmade systems, thereby, embracing mistakes as a means of evolutionary mutation.



In another celebrated essay, “On Transcendental Metaworry,” Thomas explores human anxiety, using the example of prehistoric man to demonstrate how anxiousness can overwhelm one’s mind. Thomas uses the example of opposable thumbs on human beings as a point of contention among early cavemen. He imagines a time when cavemen might have argued over their anatomically altered hands, different from all other species, as being a potential hindrance rather than a benefit. By making this observation, Thomas once again reinforces the need for mistakes in nature in order to evolve. Thomas goes on to reject immediate paths of enlightenment, noting how worry has always been at the center of the human mind, acting as a safeguard against mistakes and functioning as a catalyst for evolution. Just as a physical mutation can alter the evolution of a species, Thomas believes anxiety can do similar for the human mind.

In “The Youngest and Brightest Thing Around,” Thomas takes an optimistic look at the subject. He suggests that the human condition may not be as absurd and arbitrary as one might think, but might actually mean we are “engaged in the formation of something like a mind for the life of this planet.” He notes that, if true, we are still in the nascent stage “fumbling with language and thinking, but infinitely capacitated for the future…we are the newest, the youngest and the brightest thing around.” In “On the Magic of Medicine,” Thomas challenges the notion of prolonging one’s lifespan by exercising and eating a good breakfast every morning. Using statistical breakdowns, he concludes that this way of thinking is a “kind of enhancement, pure magic.” Since people tend not to trust skeptics, little has changed this way of thinking among the masses. Only when people recognize this as a mistake can they begin to think differently and evolve.

Other whimsical essays include Thomas’s musings on etymology, punctuation, semicolons, dermatological warts, electronic music, as well as a rebuking of physician wages in the 1950s. Through it all, however, is the insistence that human evolution is dependent on making mistakes, which ought to be treated as a feature of the human condition rather than a bug.



Dr. Lewis Thomas was an American physician, poet, essayist, etymologist, teacher, and researcher. He became the Dean of Yale Medical School and NYU School of Medicine, as well as the President of Memorial Sloan-Kettering Institute. His first collection of essays, The Lives of a Cell, won the 1974 National Book Award. Thomas published five additional works, including The Medusa and the Snail, Late Night Thoughts on Listening to Mahler’s Ninth Symphony, The Youngest Science, Et Cetera, Et Cetera, and The Fragile Species. The Lewis Thomas Prize is annually bestowed by The Rockefeller University to a scientist for artistic accomplishment.