Cardinal Luigi of Este, attracted by his brilliant reputation, offered him a post in his household and an introduction to the Court of Ferrara. The dazzling offer was accepted by the poet; but the kindness of the Cardinal had results more fatal than could have attended the machinations of his bitterest enemies.

At first all went well. Tasso produced a favourable impression upon the Duke Alfonso and upon his two sisters, Lucrezia and Eleonora. He accompanied the Cardinal on a mission to the Court of Charles IX of France, and after a year's sojourn in Paris, where he was fêted by the leading authors, including Ronsard, then at the height of his fame, he returned to Ferrara to receive new proofs of the favour of the Duke. But the more he rose in the estimation of his master, the more he excited the jealousy of those who were equally ambitious but less successful. There is, indeed, no truth in the popular legend of his love for the Princess Eleanora. The object of his affections appears to have been a lady of the Court, Leonora Scandiano. The poet Guarini was also in love with this lady, and bitter hostility resulted from the rivalry of the two poets. The malignant envy of his opponents was excited by the brilliant success of his pastoral play, Aminta, produced in 1573. So much was that poem talked of, that the Princess Lucrezia, who had meanwhile married the Duke of Urbino, sent for Tasso to read it to her at Pesaro. So pleased was she both with the work and the writer, that she invited him to pass the summer at her palace of Castel Durante. The exquisite beauty of the gardens and the grounds is said to have been in his mind when he described the gardens of Armida in the Gerusalemme.

This was the happiest time of Tasso's life. He was honoured with the favour of the highest in the land, and with the admiration of the whole of Italy. He was congenially employed on the completion of the great epic which was to make his name immortal. Never was a poet placed in a more brilliant position, nor more apparently certain of a splendid and triumphant career.

But the seeds of evil were already sown, and the mischief soon became apparent. He completed the Gerusalemme in 1575, and from that moment his peace of mind was gone. Whether he overworked himself in that great task, or whether he had secret causes of annoyance and humiliation, of which his biographers know nothing, it is difficult to conjecture, but from that period his temper seems to have become morbidly suspicious and irritable. He was painfully sensitive to criticism, and he harassed himself and others by perpetually altering and correcting passages to which objection had been taken. When at last the poem was published, which was not until some time after its completion, it was attacked by the Accademia della Crusca with considerable harshness and unfairness. The great fault found by the Academy was that the idiom was not always purely Tuscan. The very first line of the first Canto was singled out for censure:

"Canto l'arme pietose e il Capitano."

The poet uses the word "pietose" in the sense of 'pious," whereas the Academy contended that it could never mean anything but "compassionate."

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.

Unhappily, this advice was rejected; but to be perfectly just in our estimate of Tasso's conduct, we must bear in mind the position of men of letters of the Sixteenth Century in Italy. The complete absence of copyright law made it impossible for even the most popular writer to derive emolument from his books, for as soon as they acquired any popularity, they were shamelessly pirated all over the Peninsula. Enormously popular as they were, even during their lifetime, it does not appear that either Ariosto or Tasso ever profited to the extent of even one scudo by the sale of their poems. Thus a writer, unless he possessed ample means, or held some lucrative office, was entirely dependent for his bread on the fickle favour of the great. Tasso, in consequence of the reverses experienced by his father and the sequestration of his property, was absolutely devoid of anything he could call his own, and owed even the barest necessaries of life to the bounty of the Prince whom his violent conduct had, it must be admitted, justly offended. Great as his reputation was, he might well doubt whether any other sovereign in Italy would extend to him even a quarter of similar favour after the reckless and violent conduct of which he had been guilty.