David O'Connell's study seeks to serve as the final word on which version of the Enseignements de saint Louis can claim ultimate authenticity. Through an analytical comparison of the three families of the Teachings and a historical overview of the critical controversy surrounding the texts, O'Connell argues for the authority and historicity of the Noster manuscript.In this study the author has consulted all the manuscripts pertinent to the problem, reviewed the critical controversy that has surrounded these texts since the end of the Middle Ages, and furnished a critical text of the long-neglected manuscript that reproduces both the spirit and the letter of Louis' holograph.