Pierre Hadot (1922–2010) was a French philologist and a historian of ancient philosophy. He researched widely on Greek, Roman, and Hellenistic philosophy and on Latin Patristics, and he also developed an original philosophical mode of thought which puts contemporary and ancient philosophy into dialogue with each other. At the core of his philosophy is the concept of spiritual exercises, which allows Hadot to gain a better understanding of ancient philosophical texts and to interpret ancient philosophy as a way of life. For Hadot, this definition of philosophy still has a relevance and, via a number of figures (Montaigne, Goethe, Nietzsche, Bergson, Thoreau) it has traveled from antiquity to the present day.