James Duncan, preaching with great unction and power, was asked what was the secret of such powerful preaching. "The secret," he said, was "thirteen hours of consecutive prayer."

When asked the secret of his spiritual power, Charles Spurgeon said: "Knee work! Knee work!"

Livingston of Shotts, on two different occasions, preached with such power that in each service 500 were converted. Both sermons were preceded by a night of …