In his renowned collection Philosophy as a Way of Life, Pierre Hadot suggests that the original aspect of philosophy as a method by which one exercises oneself to achieve a new way of living and seeing the world fails with the rise of modernity. In that period, philosophy becomes increasingly theoretical, tending toward a system. However, Hadot himself glimpses at the dawn of modernity some instances of the original aspect of philosophy still very much present, and in his wake, Michel Foucault warns that between the late 16th and early 17th centuries the philosophical question of the reform of the mind attests to a still very close link between asceticism and access to truth. This book aims to develop just such an idea by thoroughly analyzing the most representative works of the reform of the mind in the early modern period: Francis Bacon’s New Organon (1620), René Descartes’ Discourse on the Method (1637), and Baruch Spinoza’s Treatise on the Emendation of the Intellect (1677). From this analysis it will emerge that these modern works fully deserve to be counted among the tradition of philosophy as way of life. On closer inspection, the inquiries about method elaborated in these works are fully understandable only when read in the light of a broader and more complex philosophical need: to establish the spiritual conditions for accessing truth and aspiring to full self-realization.