The author of the present volume makes it clear that one of the surest indications of the sound spirituality of St. John Baptist de La Salle was the Vigour with he combated the pernicious movements which threatened a healthy spiritual life in his time. For if the French Church knew great saints in the seventeenth century it knew, too, grave dangers. It was during the lifetime of the founder of the Brothers of the Christian Schools that Jansenism, with its forbidding rigorism, made starling headway in France.