Real analysis has long served as a pons asinorum in students’ mathematical progression, dissuading would-be math majors and prospective graduate students from continuing their studies.
This is, in part, an unavoidable consequence of what professors call a “lack of mathematical maturity”: to truly grasp the nature of, say, a compact set, you must sit with subtle definitions and theorems for a long time. Not everyone possesses the requisite focus and discipline for such work.
But this is also —in the most charitable interpretation— a very much avoidable holdover from an earlier time, when typesetting challenges made figures cumbersome to produce and publishers set strict page limits. Leaf through Cauchy’s Cours d’analyse (1821) and you will not find a single graph, table, or illustration. The same holds for Rudin’s Principles of Mathematical Analysis —written 150 years later— and many other advanced calculus and real analysis textbooks used around the globe.
Although texts like Stephen Abbott's Understanding Analysis show that these conventions were in already beginning to change for the better, Cummings's Long-Form Mathematics Series marks a sea change.
Let’s take a moment to reason heuristically and do some scratch work before launching into the formal proof, you can almost hear Professor Cummings say.
Take a break and watch this video on infinite series—you'll thank me later.
Having trouble understanding pointwise convergence? Plot this function in Desmos and adjust the slider bar.
Here’s a clever pun and a historical aside to break up this particularly dry section.
These stylistic choices do pedagogical wonders for the text.
There are drawbacks to Cummings's approach. Piecing your way through Kant's Critique of Pure Reason builds intellectual stamina in ways a less opaque text never could; so too, future math PhDs are likely better served by a book written in the traditional sparse, laconic style. But for the unwashed masses trying to navigate a course that has dashed the hopes of prospective physicists, economists, and statisticians for generations, Real Analysis: A Long-Form Mathematics Textbook is a godsend.