The reform of the morals and customs of the Spanish Church was now well in train; but it formed only a part, and the smaller part, of the sovereigns’ general scheme for the promotion and safeguard of the Catholic Faith within their realms. If the foundations of a building are insecure, the beauty and strength of its walls will soon prove valueless; and Ferdinand and Isabel, regarding “right belief” as the foundation of “right action,” and identifying “right belief” with “acceptance of the doctrines and practice of the Holy Catholic Faith,” were led by logical reasoning to establish the monstrous tyranny of the Inquisition. There can be few things so pitiless as logic when carried to its extreme, and few so faulty when the conclusions concern the soul; perhaps because it is in this sphere that human intelligence most often fails to test the truth of its premises. Heresy was to the mediæval mind “the unpardonable sin”; the heretic in the language of the day, “a venomous reptile requiring to be exterminated, lest he should spread contagion by his very breath.” And in Spain this unpardonable sin was more diffused and difficult to eradicate than amongst her neighbours; for, through the centuries of reconquest, her population had been exposed to constant intercourse with races of alien creed, endowed moreover with the subtlety of mind that is the heritage of the Oriental. However high the barriers built by racial prejudice, so long as Christian, Jew, and Moor stood side by side on Spanish soil, a certain amalgamation and interchange of ideas were inevitable. The Church, jealous for the safety of the Catholic Faith, made the construction and maintenance of barriers her lifework, and issued frequent canons prohibiting mixed marriages as well as the friendly intercourse arising from shared feasts and common dwellings. This proved unavailing; and finally Jews and Moors were segregated in special quarters, called “Juderías” and “Morerías,” and compelled to wear a dress or a badge, that would distinguish them from their Christian neighbours when they walked abroad. Such legislation was to have far-reaching results, little foreseen by those who framed it, though the immediate effect was highly satisfactory. Some there were amongst the subject races, who preferred to keep their own religion and suffer ignominy, rather than accept the Faith they had learned to hate; but the majority, faced by a choice between conversion and the scorn, disabilities, and even danger, that became the daily portion of the professed Jew or Mahometan, chose the easier path. At first the movement was gradual; but an outburst of Christian fanaticism and racial prejudice towards the close of the fourteenth century, led to a general massacre of the Jews, throughout all the large cities of Spain, and this in turn to a wholesale conversion of the survivors.