Professor Thorold Rogers thinks the influences of Turgot's reasoning on Smith's mind to be easily perceptible to any reader of the _Formation and Distribution of Wealth_ and of the _Wealth of Nations_. Dupont de Nemours once went so far as to say that whatever was true in Smith was borrowed from Turgot, and whatever was not borrowed from Turgot was not true; but he afterwards retracted that absurdly-sweeping allegation, and confessed that he had made it before he was able to read English; while Leon Say thinks Turgot owed much of his philosophy to Smith, and Smith owed much of his economics to Turgot.[164] Questions of literary obligation are often difficult to settle. Two contemporary thinkers, dealing with the same subject under the same general influences and tendencies of the time, may think nearly alike even without any manner of personal intercommunication, and the idea of natural liberty of trade, in which the main resemblance between the writers in the present case is supposed to occur, was already in the ground, and sprouting up here and there before either of them wrote at all. Smith's position on that subject, moreover, is so much more solid, balanced, and moderate than Turgot's, that it is different in positive character; the extremer form of the doctrine taught by Turgot appears to have been taught also by Smith in earlier years and abandoned. At least the fragment published by Stewart of Smith's Society paper of 1755--eleven years before Turgot wrote his book or saw Smith--proclaims individualism of the extremer form, and intimates that he had taught the same views in Edinburgh in 1750. Smith had thus been teaching free trade many years before he met Turgot, and teaching it in Turgot's own form; he had converted many of the merchants of Glasgow to it and a future Prime Minister of England; he had probably, moreover, thought out the main truths of the work he was even then busy upon. He was therefore in a position to meet Turgot on equal terms, and give full value for anything he might take, and if obligations must needs be assessed and the balance adjusted, who shall say whether Smith owes most to the conversation of Turgot or Turgot owes most to the conversation of Smith? The state of the exchange cannot be determined from mere priority of publication; no other means of determining it exist, and it is of no great moment to determine it at all.