i.
Fed by this stream of thought, and developed in the warm atmosphere of medieval devotion, the idea of demoniacal possession as the main source of lunacy grew and blossomed and bore fruit in noxious luxuriance.
There had, indeed, come into the Middle Ages an inheritance of scientific thought.

The ideas of Hippocrates, Celius Aurelianus, Galen, and their followers, were from time to time revived; the Arabian physicians, the School of Salerno, such writers as Salicetus and Guy de Chauliac, and even some of the religious orders, did something to keep scientific doctrines alive; but the tide of theological thought was too strong; it became dangerous even to seem to name possible limits to diabolical power.

To deny Satan was atheism; and perhaps nothing did so much to fasten the epithet "atheist" upon the medical profession as the suspicion that it did not fully acknowledge diabolical interference in mental disease.

Following in the lines of the earlier fathers, St.
Anselm, Abelard, St.Thomas Aquinas, Vincent of Beauvais, all the great doctors in the medieval Church, some of them in spite of occasional misgivings, upheld the idea that insanity is largely or mainly demoniacal possession, basing their belief steadily on the sacred Scriptures; and this belief was followed up in every quarter by more and more constant citation of the text "Thou shalt not suffer a witch to live." No other text of Scripture--save perhaps one--has caused the shedding of so much innocent blood.
As we look over the history of the Middle Ages, we do, indeed, see another growth from which one might hope much; for there were two great streams of influence in the Church, and never were two powers more unlike each other.
On one side was the spirit of Christianity, as it proceeded from the heart and mind of its blessed Founder, immensely powerful in aiding the evolution of religious thought and effort, and especially of provision for the relief of suffering by religious asylums and tender care.
Nothing better expresses this than the touching words inscribed upon a great medieval hospital, "Christo in pauperibus suis." But on the other side was the theological theory--proceeding, as we have seen, from the survival of ancient superstitions, and sustained by constant reference to the texts in our sacred books--that many, and probably most, of the insane were possessed by the devil or in league with him, and that the cruel treatment of lunatics was simply punishment of the devil and his minions.

By this current of thought was gradually developed one of the greatest masses of superstitious cruelty that has ever afflicted humanity.