It was an honour to read A Treatise of Human Nature. Hume's simultaneously elucidating, insightful, and problem-laden discourse is a gorgeous treasure trove for the philosophically inclined. Book one, Of the Understanding, is frankly—genius—so much so that it is challenging to comprehend in its entirety—I admit that I often found myself referring to third-party sources and supplementary information to understand Hume's arguments; the book is monumental in scope; its significance so extensive and pertinent. Hume's philosophy and argumentation are so relevant to the human condition. In particular, the discussion and formulation of the problem of induction and its profound implications for how we reason; what reason have we for presuming that preceding relations between objects (i.e., causes and effects) will resemble those of unrelated, future relations between objects? Why might we infer the future to resemble the past? Though I had known of Hume's problem of induction, to read its formulation in his own words was a truly humbling and illuminating experience. I do wish to, in addition, read his formulation in The Enquiry—which, as of writing this review, I am yet to do. 

Also worthy of particular mention is Hume's fascinating characterisation, in Book 1, of how we understand and, thereafter, his discussions of impressions and ideas and their relations to memory, belief formation, knowledge, and probability. Although I suspect that Hume's characterisation of ideas exclusively arising as a consequence of impressions may be considered outdated or impoverished by many modern philosophers (particularly rationalists—that school which opposes empiricism), I nevertheless found it an exhilarating mental exercise to dive into Hume's empiricism. I found myself time and time again persuaded by his arguments! 

I particularly enjoyed Hume's discussion on cause and effect and how he tied such concepts to probability and necessity. I had never beforehand considered probability's components till I read this book—and to philosophically deconstruct the objects of probability and necessity was both a fascinating intellectual challenge and pleasure. Hume's discussion of efficacy furthermore is intriguing—certainly within the realm of challenging conventional wisdom, or the "vulgar belief", as Hume would say. 

Of note, this book is not an easy read, and I do not claim to comprehend every section utterly, nor that various controversies or differences of interpretation, discourse, and debate, though I will certainly return to it once again when I am further versed in philosophy. Also of note, the book is meandering and difficult to follow. As of now, however, these books have been a fascinating endeavour.