This is the more important as it already defines the position taken by Jefferson twelve years later during the negotiations concerning the Louisiana Purchase. It is also a reiteration of that desire of isolation which constituted the cardinal principle of American foreign policies and which had been enunciated in the Treaty of Alliance concluded with France in 1778. Jefferson had not originated the principle, since this article of the Treaty of Alliance was due to Adams, but his direct and prolonged contact with European affairs had strengthened in him the instinctive conviction that it was the only wise course for America to follow. If he had felt free to indulge in his own theory, he would have gone even further than any of his contemporaries for, as he wrote in 1785, "I should wish the United States to practice neither commerce, nor navigation, but to stand, with respect to Europe, precisely on the footing of China." Unfortunately, this was only a theory and the servants of the country were not at liberty to follow it, since "Americans have a decided taste for navigation and commerce." Being on a mission to protect and further the commerce of his fellow countrymen, Jefferson consequently thought it his duty to forget for the time being his personal preferences. In a similar way, although he strongly believed in free trade and would have seen no objection to "throwing open all the doors of commerce, and knocking its shackles", he realized that such an ideal condition could not be reached unless the European powers granted similar treatment to American goods. He therefore came to the conclusion that, "as this cannot be done for others, unless they will do it for us, and there is no great probability that Europe will do this, we shall be obliged to adopt a system which may shackle them in our ports, as they do in theirs."[179] We have here another striking instance of the close partitioning established by Jefferson between theory and practice, between his wishes as a political philosopher, and his conception of his duties as a public servant. Far from being a single-track mind, his was decidedly a double-track intellect, with two lines of thought running parallel without any apparent contradiction, for theory never seemed to have interfered with his practice. When a month later he wrote to W. W. Seward about the future of commercial relations between Ireland and America, he excellently defined his position by saying that "the system into which the United States wishes to go, was that of freeing commerce from every shackle. A contrary conduct in Great Britain will occasion them to adopt a contrary system, at least as to that island."[180]