I have to say that Dumas Malone's 5 volumes is one of the best works of nonfiction about US history I have ever read. Malone was a great stylist -- which is to say his sentences are beautifully crafted -- but also well-organized, good at presenting hypotheses & supporting argumentation, without swallowing the reader up in the arguments. And he knows the period & the other personalities extremely well. Since the books were written pretty long ago, starting in the 1940s, they are missing some of the recent, very good "revisionism" that has come along. To supplement this magnificent work, then, I would recommend the Joseph Ellis book and the Annette Gordon Reed book. The Ellis book is a sort of psychobiography that helps to show the internal contradictions in the man's thought. Jefferson was a more complex man than many of our founding fathers and later leaders, more intellectual & more self-deluded ... something that Ellis shows well. Ellis also is able to bring out some aspects of Jefferson's personality so you feel like you know him better, know him more personally, than Malone was able to do. Of course, the Reed book brings forth the incontrovertable evidence (I think) of Jefferson's relationship with Sally Hemings, indeed the high probability that he fathered 5 kids by her and must have had more than just a purely sexual relationship with her, that is absent really from both Malone & Ellis. Read all three of these works. But start with Malone. It's well worth reading all of the volumes in the set.