I noticed recently that books with the phrase “The Last Man Who Knew Everything” all share in common that their subjects lived during the period close to the Scientific Revolution, roughly between 1550 to 1700. (The examples I own are about Athanasius Kircher, a Jesuit priest born in 1602; Thomas Young, who studied topics such as optics and philology and was born in 1773; and Philadelphia area professor Joseph Leidy, who was born in 1823.)
It’s as if the Scientific Revolution — and the knowledge it spawned — killed the ability to Know Everything. Before then, it was not only possible to be a generalist or polymath (someone with a wide range of expertise) — but the weaving together of different disciplines was actually rather unexceptional. The Ancients discussed topics such as ethics, biology, and metaphysics alongside each other. The Babylonian Talmud discusses everything from astronomy and biology to morality and law, weaving them together into a single compendium.
So what changed? Scientific knowledge exploded in size, mainly due to the application of the scientific method to our surroundings. As that knowledge base and its domain experts grew exponentially, we began classifying and ordering all that we understood — from the classification taxonomy of Carl Linnaeus to manuals for categorizing mental disease. We made sense of our world by dividing information into manageable portions and distinct areas of proficiency.