But, amid all these distractions, he never lost sight of his aim. "We labor," he wrote to the patriarch Adrian, "in order thoroughly to master the art of the sea; so that, having once learned it, we may return to Russia and conquer the enemies of Christ, and free by his grace the Christians who are oppressed. This is what I shall long for to my last breath." He was vexed at making so little progress in shipbuilding, but in Holland everyone had to learn by personal experience. A naval captain told him that in England instruction was based on principles, and these he could learn in four months; so Peter crossed the sea, and spent three months in London and the neighboring towns. There he took into his service goldsmiths and gold-beaters, architects and bombardiers. He then returned to Holland, and, his ship being attacked by a violent tempest, he reassured those who trembled for his safety by the remark, "Did you ever hear of a czar of Russia who was drowned in the North Sea?" Though much occupied with his technical studies, he had not neglected policy; he had conversed with William III, but did not visit France in this tour, for "Louis XIV," says St. Simon, "had procured the postponement of his visit"; the fact being that his alliance with the Emperor and his wars with the Turks were looked on with disfavor at Versailles. He went to Vienna to study the military art, and dissuaded Leopold from making peace with the Sultan. Peter wished to conquer Kertch in order to secure the Straits of Ienikale. He was preparing to go to Venice, when vexatious intelligence reached him from Moscow.