In the weeks leading up to the devastating cholera epidemic of 1854, a sprightly, goateed gentleman nosed about the quays and wharves of the Thames. This was but one section of London he explored daily in search of the sights and sounds that he believed were essential to his work. The man was Charles Dickens, possessor of the greatest eye in English literature.1
Yet it wasn't the sun reflecting on the Thames that immediately commanded Dickens' neurosensory perceptions or, most likely, those of any of the other 2.4 million Londoners living in the most populous city on the planet, a metropolis inhabited by Victorians but designed by Elizabethans. No human eye of this era—no matter how perfect the vision it accommodated—could compete with its possessor's olfactory receptors. On the beds of billions of epithelial cells resting within the nasal passages of the millions of persons walking about and living in close proximity, there was an overwhelming bombardment of molecules carrying the stench—the miasma, they called it—created by trillions more bacterial organisms decomposing a rising tide of excrement left behind by a multitude of horses, livestock, and, of course, those 2.4 million Londoners.
Markel H. Public Health and the Public's Fascination With EpidemicsContagious Narratives. JAMA. 2007;297(20):2292-2294. doi:10.1001/jama.297.20.2292