Final answer:
The sentence that best encapsulates the central idea of Ian Mortimer’s text is about Elizabethan physicians having a different understanding from our modern viewpoint, particularly their reliance on Galen’s humoral theory instead of germ theory.
Step-by-step explanation:
The central idea of the excerpt from Ian Mortimer’s “The Time Traveler’s Guide to Elizabethan England” focuses on the contrast between Elizabethan medical understanding and our modern conceptions. The sentence that best captures the central idea is: “It is not that they are completely ignorant as to how illnesses spread—physicians believe they know perfectly well—it is rather that their understanding is very different from ours.” This encapsulates the notion that Elizabethan medical theories, heavily influenced by Galen’s humoral theory, differ fundamentally from our contemporary germ-theory based medicine.
The understanding derived from Hippocrates and further developed by Galen that health was determined by the balance of four humors persisted through the Middle Ages and into the Elizabethan era. It wasn’t until much later, with the advancements made by researchers such as John Snow and Louis Pasteur, among others, that the germ theory of disease provided a revolutionary new framework for understanding and combating illness, displacing the earlier humoral theory.