Microorganisms were observed for the first time in the seventeenth century by the Dutch scientist Antonie van Leeuwenhoek. This opened up the world of the microscopic to doctors and medical scientists for the first time and would eventually contribute to massive advancements in medical understanding and practice.

Andreas Vesalius was a Belgian physician who wrote a very important book on human anatomy called On the Fabric of the Human Body in the early sixteenth century. Vesalius produced the first accurate and detailed depiction of the human body in European history and greatly advanced the sum of medical understanding.

Up until the nineteenth century, when Louis Pasteur revolutionized our understanding of what causes diseases, it was commonly believed throughout Europe that noxious smells in the air caused and spread diseases. This theory was called the Miasmatic Theory.

The introduction of the potato in the sixteenth and seventeenth centuries dramatically improved nutrition for the poorest people in European society. Potatoes can be grown in highly variable climates. This improved nutrition in turn contributed to a massive population growth in the eighteenth and nineteenth centuries, though a potato famine would doom much of the Irish population in the nineteenth century.

Bubonic Plague, sometimes called the Black Death, devastated European society routinely from the fourteenth century to the eighteenth century. It remained occasionally threatening into the nineteenth century, but by the time the nineteenth century came to an end, improvements in sanitation and the widespread usage of quarantines rendered the plague far less threatening and virtually eradicated.

William Harvey was an English physician in the sixteenth and seventeenth centuries. He is most famous for his work On the Movement of the Heart and Blood, which explained the circulation of blood around the body. Harvey was a prolific writer on the craft of being a doctor in general and his ideas about hospitals, medical science, and medical practice were widely influential for centuries to come.

The Sadler Report was published by a British parliamentary committee in 1832. Its primary concern was alleviating poverty in industrial centers during the early years of the Industrial Revolution. Of particular importance was limiting factory working hours for children and providing safer and healthier living conditions.

Louis Pasteur was a French scientist who in the nineteenth century discovered that heating beer was enough to kill the bacteria that was responsible for causing the beer to go bad. His process of pasteurization allowed food to be preserved far more effectively and completely revolutionized the dairy industry, among others.

In the early years of the Industrial Revolution, the urban centers of Europe were filthy, and the mortality rates from disease were very high. In Britain, social reformers like Edwin Chadwick and, earlier, Jeremy Bentham worked to improve sanitation and living conditions for the very poor. The frequent eruption of the disease cholera provided the necessary impetus for the British government to adopt the Public Health Act of 1848, which focused on providing clean running water and an efficient and sanitary sewage system. It would have dramatic effects on the mortality rate of urban Britain.

Jenner noted that milkmaids who received cowpox were protected against smallpox. He inoculated an eight-year old boy by infecting him first with cowpox. He later observed that when Philipps was exposed to smallpox he did not become infected. The smallpox vaccine was the first sucsessful vaccine in history, and thus one of the most important scientific developments in history.