Final answer:
The phrase highlights Dr. John Snow's diligent and careful approach to studying the cholera outbreak of 1854, which led to groundbreaking discoveries in public health and the germ theory of disease.
Step-by-step explanation:
The phrase 'Snow spent hours every night in his study, poring over the data they’d collected' conveys that Dr. John Snow was a dedicated and meticulous researcher. His methodical examination of data was critical to identifying the source of the cholera outbreak in 1854 London. Snow’s efforts in epidemiology included creating a map showing cholera cases around the Broad Street water pump, implementing an early form of data analysis to support his hypothesis about waterborne diseases. His work not only demonstrated the importance of sanitary water systems but also supported the germ theory of disease, which was a revolutionary concept at the time.