The pursuit of a purely historical figure—a historian, plain and simple—on the life of Nicolás León has resulted in this book. Crafted with both historical canon and imagination, it reconstructs the social, familial, political, and professional trajectory of a polymath whose tireless work is a fundamental part of Mexico's scientific tradition, a tradition that influenced various epistemic communities of the 20th century. In this work, Fernando González Dávila presents the fruit of an investigation focused on the life and work of someone widely recognized in the scientific field, about whom countless pages have been written. Hence the challenge of offering a proactive and innovative approach to understanding the figure and, simultaneously, revealing the social context of the late 19th and early 20th centuries in which this story unfolds. The author resolves this challenge with arduous and meticulous work, employing a narrative that will be discussed, criticized, and surpassed, but which, we predict, will soon become essential for reflecting on our scientific memory.