The enchanters may be able to rob me of good fortune, but of fortitude and courage they cannot.
Now one of the instances in which this knight most conspicuously showed his prudence, worth, valour, endurance, fortitude, and love, was when he withdrew, rejected by the Lady Oriana, to do penance upon the Pena Pobre, changing his name into that of Beltenebros, a name assuredly significant and appropriate to the life which he had voluntarily adopted.
…and waited to hear the ’Yes’ uttered by which Luscinda owned herself his betrothed: I am he who had not courage enough to see how her fainting fit ended, or what came of the paper that was found in her bosom, because my heart had not the fortitude to endure so many strokes of ill-fortune at once; and so losing patience I quitted the house, and leaving a letter with my host, which I entreated him to place in Luscinda’s hands, I betook myself to these solitudes, resolved to end here…
"If it goes by good name and fame," said the bachelor, "your worship alone bears away the palm from all the knights-errant; for the Moor in his own language, and the Christian in his, have taken care to set before us your gallantry, your high courage in encountering dangers, your fortitude in adversity, your patience under misfortunes as well as wounds, the purity and continence of the platonic loves of your worship and my lady Dona Dulcinea del Toboso-"
There are no more uses of "fortitude" in the book.