He was moreover sensitive in his own way to the various spiritual movements that swept over the country. This was the period of wild revivals, when religion, entering into the converted soul with inconceivable violence, found expression in gasping shrieks, rigid faintings, and strong convulsions; and the leader of this movement, strange as it may seem, was a warm friend of Franklin's. George Whitefield first visited Philadelphia in 1739, and immediately filled the city with enthusiasm by his powerful oratory. Franklin was astonished at the hold he got on the people, especially as he assured them they were naturally half beasts and half devils; but our philosopher admits that he himself succumbed once to the preacher's spell. Whitefield was preaching a begging sermon for a project which Franklin did not approve, and the latter made a silent resolve that he would not contribute. He had in his pocket a handful of copper money, three or four silver dollars, and five pistoles in gold. As the orator proceeded, he began to soften and concluded to give the copper. Another stroke of eloquence made him ashamed of that and determined him to give the silver; and the peroration was so admirable that he emptied his pocket wholly into the collector's dish, gold and all. But he was never too much carried away to omit analyzing and observing; and on one occasion, when Whitefield was preaching in the open air, he calculated by a clever experiment that the speaker might be heard by more than thirty thousand persons. Nor did he suffer Whitefield's cant phrases to pass unchallenged. At one time he invited the preacher to stop at his house, and Whitefield in accepting declared that if Franklin made the kind offer for Christ's sake he should not miss of a reward. To which the philosopher replied: "Don't let me be mistaken; it was not for _Christ's_ sake, but for _your_ sake."