The mutual interest taken by the Earl of Arundel and Harvey in old Parr may have led to the friendship which existed between the two men; perhaps, too, Lord Arundel--the prince of art collectors, to whom we owe the Arundel marbles--had detected in Harvey some similar love of art which rendered him a kindred spirit. It is clear that some bond of union existed, for in the following year--1636--Lord Arundel was sent to Vienna as Ambassador Extraordinary to the Emperor Ferdinand in connection with the peace which the Protestant States of Germany had concluded in 1635. The mission left England in April, 1636; and the Clarendon State Papers contain a letter dated from Cologne in May in which Lord Arundel speaks of a visit to the Jesuits' new college and church, where he says "they received me with all civility," and then adds jokingly, "I found in the College little Doctor Harvey, who means to convert them." There are no means of knowing when or why Harvey left England, but he seems to have attached himself to the Embassy and to have visited with it the principal cities on the way to Vienna. He used the opportunity to make the acquaintance of the leading scientific men in Germany, as he had already introduced himself to those in France on a former journey. On the 20th of May, 1636, he was at Nuremberg, where he wrote to Caspar Hofmann offering to demonstrate the circulation of the blood. He has heard, he says, that Hofmann complained of his theory, that "he impeached and condemned Nature of folly and error, and that he had imputed to her the character of a most clumsy and inefficient artificer in suffering the blood to become recrudescent, and making it return again and again to the heart in order to be reconcocted only to grow effete again in the arterial system: thus uselessly spoiling the perfectly made blood merely to find her something to do." Tradition says that Harvey actually gave this demonstration in public, and that it proved satisfactory to every one except to Hofmann himself. The old man--then past the grand climacteric--remained unconvinced, and as he continued to urge objections Harvey at length threw down his knife and walked out of the theatre.