# A Letter to Adam Smith LL.D. on the Life, Death, and Philosophy of his friend David Hume Esq./Postscript

POSTSCRIPT.
AS it is possible, Sir, nay, probable, that this little tract, because it is a little one, may be perused by many, who have not leisure or inclination to go through large volumes, and yet wish to know what Mr. Hume's philosophical system is; I shall here subjoin a short, but comprehensive summary of the doctrines which compose it, drawn up, some few years ago, by a learned gentleman, for his amusement, with proper references to those parts of our philosopher's works, where such ​doctrines were to be found. And though I never heard, the compiler had the thanks of Mr. Hume for so doing, yet neither could I ever find, that he or his friends disputed the fidelity and accuracy with which it was done.
a summary of Mr. hume's doctrines, metaphysical and moral.
OF THE SOUL.
That the soul of man is not the same this moment, that it was the last; that we know not what it is; that it is not one, but many things; and that it is nothing at all.
​That in this soul is the agency of all the causes that operate throughout the sensible creation; and yet that in this soul there is neither power nor agency, nor any idea of either.
That matter and motion often be regarded as the cause of thought.
OF THE UNIVERSE.
That the external world does not exist, or at least, that it's existence may reasonably be doubted.
That the universe exists in the mind, and that the mind does not exist.
​That the universe is nothing but a heap of perceptions, without a substance.
That though a man could bring himself to believe, yea, and have reason to believe, that every thing in the universe proceeds from some cause; yet it would be unreasonable for him to believe, that the universe itself proceeds from a cause.
Of Human Knowlege.
That the perfection of human knowlege is to doubt.
That we ought to doubt of every thing, yea, of our doubts themselves, and therefore, the utmost that philosophy can do, ​is to give us a doubtful solution of doubtful doubts.
That the human understanding, acting alone, does entirely subvert itself, and prove by argument, that by argument nothing can be proved.
That man, in all his perceptions, actions, and volitions, is a mere passive machine, and has no separate existence of his own, being entirely made up of other things, of the existence of which he is by no means certain; and yet, that the nature of all things ​depends so much upon man, that two and two could not be equal to four, nor fire produce heat, nor the sun light, without an act of the human understanding.
OF GOD.
That it is unreasonable to believe God to be infinitely wise and good, while there is any evil or disorder in the universe.
That we have no good reason to think the universe proceeds from a cause.
That as the existence of the external world is questionable, we are at a loss to find arguments by which we may prove ​the existence of the Supreme Being, or any of his attributes.
That when we speak of Power, as an attribute of any being, God himself not excepted, we use words without meaning.
That we can form no idea of power, nor of any being endued with power, much less of one endued with infinite power; and that we can never have reason to believe, that any object, or quality of any object exists, of which we cannot form an idea.
OF THE MORALITY HUMAN ACTIONS.
That every human action is necessary, and could not have been different from what it is.
That moral, intellectual, and corporeal virtues are nearly of the same kind—In other words, that to want honesty, and to want understanding, and to want a leg, are equally the objects of moral disapprobation.
That adultery must be practised, if men would obtain all ​the advantages of life; that, if generally practised, it would in time cease to be scandalous; and that, if practised secretly and frequently, it would by degrees come to be thought no crime at all.
Lastly, as the soul of man, according to Mr. Hume, becomes every moment a different being, the consequence must be, that the crimes committed by him at one time, cannot be imputable to him at another.
​I believe, Doctor Smith, the reader is now fully prepared to enter into the spirit of your concluding sentence, which therefore shall be mine.
"I have always considered Mr. Hume, both in his lifetime, and since his death, as approaching as nearly to the idea of a perfectly wise and virtuous man, as perhaps the nature of human frailty will permit."
THE END.
* ↑ The fourth section of Mr. Hume's Essays on the Human Understanding, is called, Sceptical doubts concerning the operations of the human understanding; and the fifth section bears this title, Sceptical solution of those doubts.
* ↑ The poor prodigal Gentile, in the parable, was hardly reduced to feed upon such husks as these. How good and how joyful a thing must it be, for one, that has been so reduced, to return to the house of his heavenly Father, where there is bread enough, and to spare—to know the only true God, and Jesus Christ, whom he hath sent!
* ↑ "My Enquiry concerning the Principles of Morals is of all my writings, historical, philosophical, or literary, incomparably the best." Life, p. 16.