Let us first emphatically protest that it is a question for us of the necessary defence of science and reason against the vigorous attacks of the Christian Church and its vast army, not of an unprovoked attack of science on religion. And, in the first place, our defence must be prepared against Romanism or Ultramontanism. This "one ark of salvation," this Catholic Church "destined for all," is not only much larger and more powerful than the other Christian sects, but it has the exceptional advantage of a vast, centralized organization and an unrivalled political ability. Men of science are often heard to say that the Catholic superstition is no more astute than the other forms of supernatural faith, and that all these insidious institutions are equally inimical to reason and science. As a matter of general theoretical principle the statement may pass, but it is certainly wrong when we look to its practical side. The deliberate and indiscriminate attacks of the ultramontane Church on science, supported by the apathy and ignorance of the masses, are, on account of its powerful organization, much more severe and dangerous than those of other religions. In order to appreciate correctly the extreme importance of Christianity in regard to the entire history of civilization, and particularly its fundamental opposition to reason and science, we must briefly run over the principal stages of its historical evolution. It may be divided into four periods: (1) primitive Christianity (the first three centuries), (2) papal Christianity (twelve centuries, from the fourth to the fifteenth), (3) the Reformation (three centuries, from the sixteenth to the eighteenth), and (4) modern pseudo-Christianity. I.--PRIMITIVE CHRISTIANITY Primitive Christianity embraces the first three centuries. Christ himself, the noble prophet and enthusiast, so full of the love of humanity, was far below the level of classical culture; he knew nothing beyond the Jewish traditions; he has not left a single line of writing. He had, indeed, no suspicion of the advanced stage to which Greek philosophy and science had progressed five hundred years before.