Excellent starter book for the ignorant, which is me.
A Short History of Medicine lays out the basics of medicine nice and concisely from early history to today. The summary explanations are plain and simple, making it easy for the uninitiated to grasp. Key historical figures are illuminated just enough to show their accomplishments, as well as their failures and infamous dabblings, without ever getting too in-depth and bogging down the narrative flow. It makes for a great leaping off point for those who wish to get their bearings and then move on to a deeper learning.