After the Christian conquest, their success drew down upon them the envy and hatred of their less flourishing fellow subjects, who resented also that profuse ostentation of apparel and equipage to which the Jewish character has always inclined. Their widespread practice of usury was a still more fruitful cause for detestation. Often large sums were loaned, for which exorbitant rates of interest were charged, owing to the scarcity of specie and the great risk of loss inherent to the business. As much as twenty, thirty-three, and even forty per cent. per annum was exacted and paid. The general animosity was such that a fanatical populace, smarting under a sense of wrong, and urged on by a no less fanatical clergy broke out at times into violence, and fiercely attacked the Jews in the principal cities. The Juderías, or Jewish quarters, were sacked, the houses robbed of their valuable contents, precious collections, jewels and furniture were scattered abroad, and the wretched proprietors were massacred wholesale, irrespective of sex and age. According to the historian, Mariana, fifty thousand Jews were sacrificed to the popular fury in one year, 1391, alone.

This was the turning point in Spanish history. Fanaticism once aroused, did not die until all Jews were driven out of Spain. It brought into being another class also, the Conversos, or "New Christians," i. e. Jews who accepted Christian baptism, though generally without any spiritual change. At heart and in habits they remained Jews.

The law was invoked, too, to aggravate their condition. Legislative enactments of a cruel and oppressive kind were passed. Jews were forbidden to mix freely with Christians, their residence restricted to certain limited quarters, they were subject to irksome, sumptuary regulations, debarred from all display in dress, forbidden to carry valuable ornaments or wear expensive clothes, and they were held up to public scorn by being compelled to appear in a distinctive, unbecoming garb, the badge or emblem of their social inferiority. They were also interdicted from following certain professions and callings. They might not study or practise medicine, might not be apothecaries, nurses, vintners, grocers or tavern keepers, were forbidden to act as stewards to the nobility or as farmers or collectors of the public revenues, although judging from repeated re-enactments, these laws were evidently not strictly enforced, and often in some districts were not enforced at all.

Fresh fuel was added to the fiery passions vented on the Jews by the unceasing denunciation of their heresy and dangerous irreligion, and public feeling was further inflamed by grossly exaggerated stories of their hideous and unchristian malpractices. The curate of Los Palacios has detailed some of these in his "Chronicle," and they will serve, when quoted, to show what charges were brought against the Jew in his time. "This accursed race (the Israelites)," he says, speaking of the proceedings taken to bring about their conversion, "were either unwilling to bring their children to be baptised, or if they did, they washed away the stain on the way home. They dressed their stews and other dishes with oil instead of lard, abstained from pork, kept the passover, ate meat in Lent, and sent oil to replenish the lamps of their synagogues, with many other abominable ceremonies of their religion. They entertained no respect for monastic life, and frequently profaned the sanctity of religious houses by the violation or seduction of their inmates. They were an exceedingly politic and ambitious people, engrossing the most lucrative municipal offices, and preferring to gain their livelihood by traffic, in which they made exorbitant gains, rather than by manual labour or mechanical arts. They considered themselves in the hands of the Egyptians whom it was a merit to deceive and rob. By their wicked contrivances they amassed great wealth, and thus were able often to ally themselves by marriage with noble Christian families."

The outcry against the Jews steadily increased in volume. The clergy were the loudest in their protests against the alleged abominations, and one Dominican priest, Alonso de Hojeda, prior of the monastery of San Pablo in Seville, with another priest, Diego de Merlo, vigorously denounced the "Jewish leprosy" so alarmingly on the increase and besought the Catholic sovereigns to revive the Holy Office with extended powers as the only effective means of healing it. The appeal was strongly supported by the papal nuncio at the Court of Castile. Ferdinand and Isabella, as devout Catholics, deplored the prevalence of heresy, which they acknowledged to be rampant, and yet they hesitated to surrender any of their independence. No other state in Europe was so free from papal control or interference. Some of the Conversos held high places about the court and they, of course, used every effort to strengthen the reluctance of the queen, particularly. On the other hand, the Dominican monk, Thomas de Torquemada, her confessor in her youth, strove to instil the same spirit of unyielding fanaticism that possessed himself, and earnestly entreated her to devote herself to the "extirpation of heresy for the glory of God and the glorification of the Catholic faith." She long resisted but yielded at last to the unceasing importunities of the priests around her, and consented to solicit a bull from the pope, Sixtus IV, to introduce the Modern Inquisition into Castile. It was issued, under the date of November 1st, 1478, and authorised the appointment of two or three ecclesiastical inquisitors for the detection and suppression of heresy throughout Spain.

One difference from the usual form establishing such tribunals was the location of the power of appointment of inquisitors, which was vested in the king and queen instead of in Provincials of the Dominican or Franciscan Orders. Heretofore the appointment of inquisitors had been considered a delegation of the authority of the Holy See, something entirely independent of the secular power. But so jealous of outside interference were the Spanish rulers and the Spanish people, that the pope was forced to give way. Though he and his successors vainly strove to recover the power thus granted, they were never entirely successful, and the Spanish Inquisition remained to a large extent a state affair, and this fact explains much which otherwise is inexplicable. For example the confiscations passed into the royal instead of into the papal treasury.

At first mild measures were to be tried. Cardinal Mendoza, Archbishop of Seville, had drawn up a catechism instructing his clergy to spare no pains in illuminating the benighted Israelites by a candid exposition of the true principles of Christianity. Progress was slow, and after two years the results were so meagre that it was thought necessary to proceed to the nomination of inquisitors, and two Dominican monks, Fra Miguel de Morillo, and Juan de San Martin, were appointed with full powers, assisted by an assessor and a procurator fiscal.

The Jews played into the hands of their tormentors. Great numbers had been terrified into apostasy by the unrelenting hostility of the people. Their only escape from the furious attacks made upon them had been conversion to Christianity, often quite feigned and unreal. The proselytising priests, however, claimed to have done wonders; one, St. Vincent Ferrer, a Dominican of Valencia, had by means of his eloquence and the miraculous power vouchsafed him, "changed the hearts of no less than thirty-five thousand of house of Judah." These numerous converts were of course unlikely to be very tenacious in their profession of the new faith, and not strangely laid themselves open to constant suspicion. Many were denounced and charged with backsliding, many more boldly reverted to Judaism, or secretly performed their old rites. Now uncompromising war was to be waged against the backsliding "new Christians" or Conversos.

The inquisitors installed themselves in Seville, and made the Dominican convent of San Pablo their first headquarters, but this soon proved quite insufficient in size and they were allowed to occupy the fortress of the Triana, the great fortress of Seville, on the right bank of the Guadalquivir, the immense size and gloomy dungeons of which were especially suitable. This part of the city was much exposed to inundations, and when, in 1626, it was threatened with destruction by an unusually high flood, the seat of the tribunal was removed to the palace of the Caballeros Tellos Taveros in the parish of San Marco. In 1639 it returned to the Triana which had been repaired, and remained there till 1789, when further encroachments of the river caused it to be finally transferred to the College of Las Beccas. The Triana is now a low suburb, inhabited principally by gipsies and the lower classes. It was at one time the potters' quarter where the famous azulejo tiles were made, and its factories to-day produce the well known majolica vases and plates with surface of metallic lustre.