"The spirit that will lead us is a spirit of complete submission to the authorized doctrines of the Catholic Church, and, at the same time, of strict fidelity to sound scientific methods. We think that in the country of Petau, Mabillon, Tillemont, we have the right to use this kind of language." (Leonce de Grandmaison) At the threshold of a new century opening up for Recherches de Science Religieuse in this year of 2010, these lines drawn from the journal's first Editorial bear testimony both to another time, with its context of tensions in the Church around 1910, and to the fundamental project for the journal. Its founder, Leonce de Grandmaison, was right to be attentive to those tensions and to that plan. What has since then been called the "modernist crisis" had actually been named three years before in an encyclical by Pius X and, in good part, "invented" by that document in the double sense of the word, "imagined" and "discovered." At the time the first issue of the journal came out, the crisis was, if not being settled, at least in the process of being allayed. In spite of certain risks and threats, the essential part of the RSR project had been accepted and was to succeed. It is this project we would like to recall in these opening pages to a work that is meant to greet and celebrate the journal's centenary, but is also intended to trace out the perspectives for the future, however limited or risky this endeavour might be. How can we define such a project? Or better still, what part of it best opens onto the new horizons we see ahead of us in 2010?