It is difficult to overestimate the importance of Lionel Robbins's Essay on the Nature and Significance of Economic Science (Essay). But how did Robbins make his seminal arguments? And, notwithstanding Essay's extraordinary success, are these arguments sound? This essay attempts to address these questions in three Parts. Part I attempts to understand Robbins' rhetorical appeal. It argues that the persuasiveness and attraction of his arguments derive largely from an extraordinarily subtle, yet masterful, exposition of a series of beautifully-crafted polarities, each building from the next: material welfare versus scarcity, society versus individual, empiricism versus apriorism, normativity versus positivism, interpersonal comparisons versus ordinal rankings, political economy versus economic science. In each case, Robbins exposes a seeming divergence, then takes sides. He then uses this position as an anchor to make taking a position on the next polarity and seemingly natural and effortless exercise. Put simply, his scarcity-based definition of economics leads him to espouse an individualistic, aprioristic and positivist perspective on economics. This stance then naturally leads to a rejection of interpersonal comparisons of utility. Without the ability to engage in such comparisons, the scope for economic science diminishes considerably. Convenient to the status quo, welfare and social institutions are no longer within the science's purview. Part II addresses the potential objection that Part I is too crude a depiction of Robbins' position. It argues that, notwithstanding some nuances notably related to Robbins's possible ambivalence around empirical studies, the sequence is essentially accurate. Finally, Part III proceeds to show that the attractive polarities Robbins has created are flimsy. Moreover, Robbins' too often facile arguments have the ultimate effect of unnecessarily narrowing the boundaries of economics, leading unfortunately to a diminished role for the discipline in public policy. Notwithstanding these criticisms, though, Essay's enduring appeal lies in the issues it so presciently raised.