Denis became champion of Kardec’s teaching and dedicated his life to its cause. He is known by some as ‘The Apostle of Spiritsm’ and he summerised his personal mission when he stated; ‘I have consecrated this existence to the service of a Great cause, Spiritism or Modern Spiritualism that will certainly be the universal faith, and the religion of the future.’

In 1911 Leo Denis’s book La Verite sur Jeanne d’Arc. (The Truth about Joan of Arc) was published in France. The book postulated that Joan was psychically gifted and that she can only be truly understood if we accept this. In the introduction of the book the author writes; ‘To penetrate the mystery of Joan of Arc it seems to us necessary to study, and have practical knowledge of, psychic science. It is necessary to have sounded the depths of this invisible world, this ocean of life which envelops us, from which we all come at birth and into which we are replunged at death. How can writers understand Joan if their thoughts have never risen above terrestrial facts, looked beyond the narrow horizon of an inferior material world, nor caught one glimpse of the life beyond?’

Arthur Conan Doyle, an ardent psychical researcher and a proponent of Spiritualism read the book and was so impressed with it he asked Denis if he could translate it into English, and in 1924 it was published in London by John Murray under the title, The Mystery of Joan of Arc. Doyle wrote in the introduction; ‘His (Denis’s) treatment of his heroine is so complete that there is no need for me to say anything save to express my personal conviction that, next to the Christ, the highest spiritual being of whom we have any exact record upon this earth is the girl Joan. One would kneel rather than stand in her presence.’

Denis was the consolidator of Spiritism. He was not just the substitute and continuator of Allan Kardec, as is generally supposed. Denis had a mission practically as significant as the one of the Codifier. To him, was assigned the development of the doctrinaire studies, to proceed with the mediumistic research, to propel the Spiritist Movement in France and all over the world, to deepen the moral aspect of the Doctrine and above all, to consolidate it in the first decades of the Century.

In Spiritism the role of Kardec is that of the wise person and the role of Denis is that of the philosopher. Léon Denis was nominated the Apostle of Spiritism, due to his magnificent work, and the words written and spoken in behalf of the new Doctrine. He can also be denominated its consolidator, the Philosopher of Spiritism. Possessing accentuated moral qualities, he dedicated his entire existence to the defense of the postulates that Kardec had transmitted in the books of the spiritist Pentateuch.

Denis himself, summarized the mission that he had come to accomplish in favor of a noble cause: ‘I have consecrated this existence to the service of a Great cause, Spiritism or Modern Spiritualism that will certainly be the universal faith, and the religion of the future.’

Léon Denis was born in Foug, Meurthe-et-Moselle, France, on January 1, 1846, of a humble family. Very early in life out of necessity, he did manual works and had to carry the heavy responsibilities of his family. From his first steps into this world, he sensed that invisible friends assisted him.

Instead of participating in plays relating to his youth, he tried to instruct himself as intensely as possible. He read serious works, thus striving through his own efforts, to develop his intelligence, and became a serious and competent self-didactic. At the age of 18, he commenced to work as a sales representative, and because of this he had take frequent trips. This situation continued up to the time of his reformation and beyond. He adored music, and whenever he had a chance, he would attend operas or concerts. He played well-known arias at the piano and also some accords from his own inspiration. He did not smoke, and was almost exclusively a vegetarian, nor did he indulge in fermented drinks. He found water to be his ideal drink.

It was his habit to review books with interest, of those displayed in the bookstores, at the age of 18, by ‘chance’ his eyes glanced at a work with an unusual title: The Spirits’ Book by Allan Kardec. Having in his possession the amount needed to purchase the book, he bought it and rushed to his home immediately surrendering eagerly to the reading. The comments of Denis after reading it: ‘I found in this book the clear solution, complete and logical, to a universal problem. My conviction became strong and sound. The Spiritist Theory dissipated my indifference and my doubts.’