Here he composed his first work, the _Treatise of Human Nature_; though it would appear from the following passage in the letter to Cheyne, that he had been accumulating materials to that end for some years before he left Scotland.
"I found that the moral philosophy transmitted to us by antiquity laboured under the same inconvenience that has been found in their natural philosophy, of being entirely hypothetical, and depending more upon invention than experience: every one consulted his fancy in erecting schemes of virtue and happiness, without regarding human nature, upon which every moral conclusion must depend." This is the key-note of the _Treatise_; of which Hume himself says apologetically, in one of his letters, that it was planned before he was twenty-one and composed before he had reached the age of twenty-five.[5] Under these circumstances, it is probably the most remarkable philosophical work, both intrinsically and in its effects upon the course of thought, that has ever been written.

Berkeley, indeed, published the _Essay Towards a New Theory of Vision_, the _Treatise Concerning the Principles of Human Knowledge_, and the _Three Dialogues_, between the ages of twenty-four and twenty-eight; and thus comes very near to Hume, both in precocity and in influence; but his investigations are more limited in their scope than those of his Scottish contemporary.
The first and second volumes of the _Treatise_, containing Book I., "Of the Understanding," and Book II., "Of the Passions," were published in January, 1739.[6] The publisher gave fifty pounds for the copyright; which is probably more than an unknown writer of twenty-seven years of age would get for a similar work, at the present time.

But, in other respects, its success fell far short of Hume's expectations.

In a letter dated the 1st of June, 1739, he writes,-- "I am not much in the humour of such compositions at present, having received news from London of the success of my _Philosophy_, which is but indifferent, if I may judge by the sale of the book, and if I may believe my bookseller." This, however, indicates a very different reception from that which Hume, looking through the inverted telescope of old age, ascribes to the _Treatise_ in _My Own Life_.
"Never literary attempt was more unfortunate than my _Treatise of Human Nature_.

It fell _deadborn from the press_ without reaching such a distinction as even to excite a murmur among the zealots." As a matter of fact, it was fully, and, on the whole, respectfully and appreciatively, reviewed in the _History of the Works of the Learned_ for November, 1739.[7] Whoever the reviewer may have been, he was a man of discernment, for he says that the work bears "incontestable marks of a great capacity, of a soaring genius, but young, and not yet thoroughly practised;" and he adds, that we shall probably have reason to consider "this, compared with the later productions, in the same light as we view the juvenile works of a Milton, or the first manner of a Raphael or other celebrated painter." In a letter to Hutcheson, Hume merely speaks of this article as "somewhat abusive;" so that his vanity, being young and callow, seems to have been correspondingly wide-mouthed and hard to satiate.
It must be confessed that, on this occasion, no less than on that of his other publications, Hume exhibits no small share of the craving after mere notoriety and vulgar success, as distinct from the pardonable, if not honourable, ambition for solid and enduring fame, which would have harmonised better with his philosophy.