Philosophy in antiquity was conceived not as mere theory but as a way of life; but it lost its 'practicist' cast through a process that begins in the patristic era and peaks with its conversion into an academic discipline in the medieval universities under the influence of 13th-century scholasticism. Juliusz Domanski sets out the reasons behind that process and shows how traces of the 'practicist' orientation survived, ultimately leading to a recovery of the ancient notion among the humanists of the Renaissance. A foreword by Pierre Hadot relates Domanski's research to his own vision of the history of philosophy.