Read some of his Journal entries:
"I advised one who had been troubled many years with a stubborn paralytic disorder to try a new remedy. Accordingly, she was electrified and found immediate help. By the same means I have known two persons cured of an inveterate pain in the stomach; and another of a pain in his side which he had had ever since he was a child. Nevertheless, who can wonder that many gentlemen of the faculty, as well as their good friends, the apothecaries, decry a medicine so shockingly cheap and easy, as much as they do quick-silver and tar-water?" (January 20, 1753)
"Having procured an apparatus on purpose, I ordered several persons to be electrified who were ill of various disorders; some of whom found an immediate, some a gradual, cure. From this time I appointed, first some hours in every week and afterward an hour in every day, wherein any that desired it might try the virture of this surprising medicine. Two or three years after, our patients were so numerous that we were obliged to divide them: so part were electrified in Southwark, part at the Foundry, others near St. Paul’s, and the rest near the Seven Dials. The same method we have taken ever since; and to this day, while hundreds, perhaps thousands, have received unspeakable good, I have not known one man, woman, or child, who has received any hurt thereby: so that when I hear any talk of the danger of being electrified (especially if they are medical men who talk so), I cannot but impute it to great want either of sense or honesty." (November 9, 1756)
[Warning: Couldn't someone go to prison today for practicing medicine without a license?]
"At my leisure hours this week, I read Dr. Priestley's ingenious book on electricity. He seems to have accurately collected and well digested all that is known on that curious subject. But how little is that all! Indeed the use of it we know; at least, in some good degree. We know it is a thousand medicines in one: in particular, that it is the most efficacious medicine in nervous disorders of every kind which has ever yet been discovered. But if we aim at theory, we know nothing. We are soon
Lost and bewilder'd in the fruitless search." (January 4, 1768)
"I thought myself able to speak to the congregation, which I did for half an hour; but afterwards I found a pain in my left side and in my shoulder by turns, exactly as I did at Canterbury twenty years before. In the morning I could scarcely lift my hand to my head; but after being electrified I was much better, so that I preached with tolerable ease in the evening; and the next evening read the letters, though my voice was weak. From this time I slowly recovered my voice and my strength, and on Sunday preached without any trouble."
(September 19, 1773)
Wesley was a learned man interested in different fields of inquiry (such as the brilliant American preacher, Johnathan Edwards) but I think this is one area where John Wesley should have left well enough alone.
[Warning: Don't try this at home or anywhere else! Passing electrical current through your body could hurt or kill you!!]
The moral of the story: even brilliant Christians can do crazy or dangerous things!