From “The Human Condition: A User’s Manual,” by Arnold Kunst
Blood transfusions began in the 1600’s. The first known case was of a 15-year-old boy receiving about 12 ounces of sheep’s blood.
As you can imagine, in those early days the thing was hit and miss. For example, people thought that volatile, hot-tempered people could be calmed by giving them the blood of a docile sheep or a cow. Even so, there were concerns about long-term changes and mutations. Would the patient with sheep’s blood in his veins end up with a sheep's head? Samuel Pepys mused in his diary about the possibilities: "This did give occasion to many pretty wishes, as of the blood of a Quaker to be let into an Archbishop, and such like."
What was cutting-edge back then has, of course, become commonplace. We should be careful about the condescension thing, though. Like us, they were reacting to something completely new as best they could – we must honor the courage of our forebearers in much the same way that our descendents should honor our courage dealing with what, to them, may seem equally goofy.