It was not fear of persecution that led Calvin to hide himself; he was in a free city. But he had need to put himself out of the reach of the strange winds of doctrine that were then rushing over the world, and of all the sensations of one of the most troubled periods of history. He wished to withdraw himself from earthly noises, and hear only the voice of God and the music of heaven. Rapid emotions, now sorrowful, now joyful, continually repeated, as he had so often felt in Paris, neutralised each other and left nothing in his heart. He wished to fix his looks on high, and give the thoughts which descended to him from heaven the time to lay firm hold upon his mind, and become transformed into a strong and unchangeable affection, which would become the soul of his whole life. He had already learnt much; but it was not sufficient for him to learn, he must create: that was the vocation he had received from his Master, and to that end he must concentrate all the strength of his intelligence and of his heart. When God desires to form the ripe ear of corn, he proceeds slowly and silently, but powerfully. The little seed is hardly thrown into the ground when the manifold forces of different agents combine to fecundate the germ. During the coolness of the night or the heat of the day, the earth imparts her juices, the rain enriches it, and the sun-warms it.... Such was the inner process then going on in the reformer. Divine and human forces were combining to bring to maturity all the germs of beauty and strength that God had deposited in his heart, will, and understanding, and to render his genius capable of undertaking and accomplishing a great work in the world. Calvin felt that he needed silence and concentration. Destined to become one of God's mightiest instruments for his age and all ages to come, it was necessary for him to live alone with God, that he should have God in him, and that the divine warmth should so melt and purify all his natural energies, as to fit him for the accomplishment of his immense task. 'Ah!' said he, without thinking of himself, 'God wishing to publish his law by Moses, led him to Sinai and took him into his heavenly closet.'[321] Many of God's ministers have, after Moses, been thus prepared for the work of their office. Luther had been carried away to the Wartburg: Basle was Calvin's Wartburg, still more than Angoulême. He had, however, one acquaintance, or rather an intimate friend in that city. This was Nicholas Cop, ex-rector of the university of Paris, and now a refugee at Basle. How could Calvin, who had been the innocent cause of his exile, remain long within the same walls without seeing him? While preserving his incognito with respect to the public, he called upon his dear fellow-soldier, and the latter saw that pale familiar face enter his room. The friends now visited each other and conversed together; but mystery for some time longer shrouded the person of the young reformer.