This book of Pere Grou is the work is a master of the spiritual life who speaks in a clear and decisive manner, as only those can who are thoroughly acquainted with their subject. But it should be understood by those who read it that it is not intended for beginners, but for such as have made some sort of progress in a knowledge of the spiritual life. For much that he says is put so tersely that those whose knowledge of the subject is not within measurable relativity to that of the writer may easily miss the full sense of his words, and thus be led to look on some parts and passages as unreal or unmeaning or at least exaggerated.