At first I wondered, how can a math text be "lively?" But it really is; I even found myself chuckling a few times.<br>The book is very gradual, and assumes at first you know almost nothing about math (aside from like basic calculus), and it is not overly formal with the notation, which is often a barrier to the natural flow of the text in other books.<br>I liked it so much that, even though I had the digital version, I bought the physical version to go on my shelf.