The son of a famous professor of ethics, one who scarcely ever opened his lips without mentioning the categorical imperative, was lamenting to me one day the fact that he lived in a desolating dryness of spirit, in a state of inward emptiness. And I was constrained to answer him thus: "My friend, your father had a subterranean river flowing through his spirit, a fresh current fed by the beliefs of his early childhood, by hopes in the beyond; and while he thought that he was nourishing his soul with this categorical imperative or something of that sort, he was in reality nourishing it with those waters which had their spring in his childish days. And it may be that to you he has given the flower of his spirit, his rational doctrines of ethics, but not the root, not the subterranean source, not the irrational substratum." How was it that Krausism took root here in Spain, while Kantism and Hegelianism did not, although the two latter systems are much more profound, morally and philosophically, than the first? Because in transplanting the first, its roots were transplanted with it. The philosophical thought of a people or a period is, as it were, the flower, the thing that is external and above ground; but this flower, or fruit if you prefer it, draws its sap from the root of the plant, and this root, which is in and under the ground, is the religious sense. The philosophical thought of Kant, the supreme flower of the mental evolution of the Germanic people, has its roots in the religious feeling of Luther, and it is not possible for Kantism, especially the practical part of it, to take root and bring forth flower and fruit in peoples who have not undergone the experience of the Reformation and who perhaps were incapable of experiencing it. Kantism is Protestant, and we Spaniards are fundamentally Catholic. And if Krause struck some roots here--more numerous and more permanent than is commonly supposed--it is because Krause had roots in pietism, and pietism, as Ritschl has demonstrated in his _Geschichte des Pietismus_, has specifically Catholic roots and may be described as the irruption, or rather the persistence, of Catholic mysticism in the heart of Protestant rationalism. And this explains why not a few Catholic thinkers in Spain became followers of Krause. And since we Spaniards are Catholic--whether we know it or not, and whether we like it or not--and although some of us may claim to be rationalists or atheists, perhaps the greatest service we can render to the cause of culture, and of what is of more value than culture, religiousness--if indeed they are not the same thing--is in endeavouring to formulate clearly to ourselves this subconscious, social, or popular Catholicism of ours. And that is what I have attempted to do in this work.