Tasso was not only worried by these minute quibbles, but he was also haunted by the dreadful apprehension that his religious orthodoxy might be impugned, and he himself applied to the Fathers of the Holy Inquisition for an examination and a vindication. In vain the Fathers assured him with unanimous cordiality that such a process was utterly superfluous, and that the purity of his faith had never for a moment been held in doubt; he still professed himself dissatisfied, and he long continued to torment himself with religious scruples. The Duke of Ferrara, doubtless highly gratified at the success of the masterpiece of his Court Poet, appointed Tasso his private secretary when that post became vacant through the death of Giambattista Pigna in 1577. Probably the arduous duties and the heavy responsibilities of this appointment weighed him down with a fresh load of anxiety, and he may have felt that he had become more than ever the object of malice and envy; whatever the cause, excitability verging on frenzy, and suspicion verging on madness betrayed themselves more and more in his speech and actions. He fancied, perhaps not without reason, that some of his letters had been intercepted; he firmly believed, though with less foundation, that there was a plot to poison him. He had also the annoyance, peculiarly galling to an author, of knowing that spurious copies of his great epic were being circulated throughout Italy, full of mistakes and interpolated passages. All these causes of uneasiness culminated in frightful violence in the month of June of that fatal year. One evening in the apartments of the Princess Lucrezia, and even in her presence, he drew a dagger and stabbed a manservant whom he suspected of being concerned in the robbery of some missing documents. He was arrested, and the Duke ordered him to be kept a close prisoner. When released from captivity, he was so excited with grief and indignation, that all observers pronounced him mad. He took refuge in a Franciscan Monastery; but when the Duke refused to receive his letters, he dreaded the effects of his master's anger, and fled from Ferrara in a pitiable condition, without his manuscripts, without sufficient clothes, and without a particle of money. He seems actually to have begged his way from Ferrara to Sorrento, near Naples, where his sister was married to Marzio Sersale. It would be difficult to find a more picturesque episode in the life of any poet than that of Tasso presenting himself to his sister in the garb of a mendicant. She received the unhappy wanderer with hospitality and affection, welcomed him in her house, and when he was sufficiently recovered from the fatigues of mind and body to discuss his affairs, gave him the sensible advice never to return to the Court of Ferrara.