Having struggled through these two dozen great novels and symphonies, I have to confess that I was unable to discern their "internal rhythms." And I don't really have a sense of how their "fleeting truths" are fleeting or why these papers are any more poetic than your average legal memo or newspaper article. They describe some of the most wonderful discoveries of the past century, but there is nothing inherently wonderful about how they do so. In fact, by the criteria you'd use to judge any other piece of writing--construction of argument, lucidity of explanation, quality of prose--a few of the papers are downright sloppy.
In part that's because the guidelines of scientific publication provide so little room to maneuver stylistically. The medium privileges precision over artistry, and efficiency over individuality. Humor and fresh prose are altogether absent from the great works Lightman has collected. The narrative of how the scientist got from point A in his thinking to point B, the story of the messy false starts and unexpected diversions that make Lightman's introductions so compelling, is obscured by the imperative to present final results with maximum economy. Scientists aren't expected to show their work unless it has direct bearing on the final results. And most of the time, you have to read between the lines just to glimpse the author's excitement about his subject.
About a quarter of the discoveries Lightman chronicles occurred by accident, or were the result of a lucky scientist being in the right place at the right time. Of course, sometimes being in the right place at the right time is a matter of more than luck. When Alexander Fleming stumbled on penicillin, it was a fortuitous accident, but one he had put himself in the way of. "Fleming dedicated himself to a kind of studied disorder," writes Lightman. His lab was a scene of constant disarray, a place where all kinds of microscopic organisms could find a home in the stacks of petri dishes that were often left out to fester, sometimes for weeks at a time. Occasionally, Fleming would check them out, just to see if anything "interesting" had shown up.
When he found a fluffy white mold growing on one of those petri dishes in the spring of 1928, he wasn't looking for what turned out to be the most important advance in the history of medicine. It's not clear that he even fully realized the implications of his discovery. Fleming's paper was titled "On the Antibacterial Action of Cultures of a Penicillium, with Special Reference to Their Use in the Isolation of B. Influenzae." The title didn't say anything about medical uses. In one sentence toward the end of the paper, Fleming mentions that penicillin "may be an efficient antiseptic for application to, or injection into, areas infected with penicillin-sensitive microbes," but he thought the more important consequence of his discovery was that scientists would be able to use the antibiotic to separate different strains of bacteria in laboratory cultures. The scientific community largely ignored Fleming's sentence about medical applications for the better part of the next decade.
Like Fleming, Ernest Rutherford more or less stumbled on the discovery of the atomic nucleus. At the time, he had been probing the innards of atoms by bombarding extremely thin pieces of gold foil with alpha particles and then observing what happened. Most of the time, the alpha particles traveled straight through the gold foil, as if passing through empty space, or were deflected only slightly. Rutherford assigned an undergraduate to perform what he later called a "damn fool experiment," to check whether any of the alpha particles were bouncing off in other, unexpected directions. No one had thought to look for such large-angle deflections, because no one expected to find them. But something suggested to Rutherford that the experiment was worthwhile.
The results of the undergraduate's fool's errand ended up laying the foundation for modern physics and chemistry. He found that a very small percentage of the particles were rebounding wildly, in every possible direction, as though they had collided with some dense concentration of mass. Rutherford inferred that atoms were not balls of plum pudding, as others had thought, but rather cavernous empty spaces with electrons buzzing around miniature nuclei.