A History of Black Death and Its Effects on Western Europe

This plague, thought to be the Bubonic plague, spread throughout Europe, killing about half its population. It was called the Black Death because of the black blotches that appeared on the victims' bodies. This plague was carried by infected fleas of the black rat.
Theology, developed in accordance with this idea, threw about all cures, even those which resulted from scientific effort, an atmosphere of supernaturalism. The vividness with which the accounts of miracles in the sacred books were realized in the early Church continued the idea of miraculous intervention throughout the Middle Ages. The testimony of the great fathers of the Church to the continuance of miracles is overwhelming; but everything shows that they so fully expected miracles on the slightest occasion as to require nothing which in these days would be regarded as adequate evidence.
In this atmosphere of theological thought medical science was at once checked. …