The most terrible scenes of the French Revolution were drawing nigh; but he laboured on, modestly and devotedly--apparently without a thought of the great political storm raging about him.
His first step was to discard utterly the whole theological doctrine of "possession," and especially the idea that insanity is the result of any subtle spiritual influence.

He simply put in practice the theory that lunacy is the result of bodily disease.
It is a curious matter for reflection, that but for this sway of the destructive philosophy of the eighteenth century, and of the Terrorists during the French Revolution, Pinel's blessed work would in all probability have been thwarted, and he himself excommunicated for heresy and driven from his position.

Doubtless the same efforts would have been put forth against him which the Church, a little earlier, had put forth against inoculation as a remedy for smallpox; but just at that time the great churchmen had other things to think of besides crushing this particular heretic: they were too much occupied in keeping their own heads from the guillotine to give attention to what was passing in the head of Pinel.

He was allowed to work in peace, and in a short time the reign of diabolism at Bicetre was ended.

What the exorcisms and fetiches and prayers and processions, and drinking of holy water, and ringing of bells, had been unable to accomplish during eighteen hundred years, he achieved in a few months.