Knox was no sooner settled in St Andrews than he resumed the system he had followed with good effect in East Lothian, causing his pupils to give account of their catechism in public to all who chose to come, and opening up in a plain and colloquial manner the Gospel of St John. His great ability and success as a teacher, and his wonderful gift of persuasive speech, thus became generally known. After private but unsuccessful efforts had been made by Balnaves and others to induce him to become colleague to John Rough, a formal call to the ministry was, with the counsel of Sir David Lindsay,[87] publicly addressed to him from the pulpit by Rough, in the name of the rest, and he was solemnly adjured not to despise the voice of God speaking to him. Thus honourably called to assume the office of a public preacher in that reformed congregation, he at last entered on the work with all his heart, and made full proof of his ministry before the assembled citizens in their parish church, as well as before the rude garrison in the castle chapel. He administered the Sacrament of the Lord's Supper in the simple form he always used, and continued the public catechising of his pupils, which the people of the town heard repeated till they had the substance of his teaching by heart, and thus was spread a knowledge of Gospel truth even among those who could not read. A very graphic account is given in his History of the sermons, catechisings, and disputations he held with the popish champions, by means of which the new doctrines gained a hold on the minds of the citizens of St Andrews which they never wholly lost. But times of trial were to come ere the cause should finally triumph in that city, or in his native land; and the earnest preacher, whose mouth God had opened in that old parish church, was to be taught by sad experience how hard it is to leave all and simply follow Christ, ere he was to be privileged to see the full fruit of his labours. [Sidenote: A Galley-slave.]