Dare we experiment on a mind which no longer belongs to us?

"I am asked sometimes to read an heretical book: well, if I believed my reading it would help its refutation, and might be an assistance to others in keeping them out of error, I might do it as a hard matter of duty, but I shall not do it unless I see some good will come of it. I am not going to drag my spirit through a ditch for the sake of having it washed afterwards, for it is not my own. It may be that good medicine would restore me if I poisoned myself with putrid meat, but I am not going to try it: I dare not experiment on a mind which no longer belongs to me. There is a mother and a child, and the child has a book to play with, and a black lead pencil. It is making drawings and marks upon the book, and the mother takes no notice. It lays down one book and snatches another from the table, and at once the mother rises from her seat, and hurriedly takes the book away, saying: “No, my dear, you must not mark that, for it is not ours.” So with my mind, intellect, and spirit; if it belonged to me I might or might not play tomfool with it, and go to hear Socinians, Ritualists, Universalists, and suchlike preach, but as it is not my own, I will preserve it from such fooleries, and the pure word shall not be mingled with the errors of men." -Taken from Flashes of Thought by C. H. Spurgeon, 1883