And this same cause enlisted also a prolific contemporary genius, called by Cervantes "that prodigy," Lopé de Vega, who commended it in a play entitled _Los Cautivos de Argel_, The Captives of Algiers. At a later day, Calderon, sometimes exalted as the Shakspeare of the Spanish stage, in one of his most remarkable dramas, _El Principe Constante_, The Constant Prince, cast a poet's glance at Christian slavery in Morocco. To these works--belonging to what may be called the literature of Anti-Slavery, and shedding upon our subject a grateful light--must be added a curious and learned volume, in Spanish, on the Topography and History of Algiers, by Haedo, a father of the Catholic Church,--_Topografia y Historia de Argel por Fra Haedo_,--published in 1612; and containing also two copious Dialogues--one on Captivity (_de la Captiudad_), and the other on the Martyrs of Algiers, (_de los Martyres de Argel_). These Dialogues, besides embodying authentic sketches of the sufferings in Algiers, form a mine of classical and patristic learning on the origin and character of slavery, with arguments and protestations against its iniquity, which may be explored with profit, even in our day. In view of this gigantic evil, particularly in Algiers, and in the hope of arousing his countrymen to the generous work of emancipation, the good father exclaims,[6] in words which will continue to thrill the soul,--so long as a single fetter binds a single slave,--"Where is charity? Where is the love of God? Where is the zeal for his glory? Where is desire for his service? Where is human pity and the compassion of man for man? Certainly to redeem a captive, to liberate him from wretched slavery, is the highest work of charity, of all that can be done in this world." [Footnote 6: Pp. 140, 141.] [Illustration] Not long after the dark experience of Cervantes, another person, of another country and language, and of a still higher character, St. Vincent de Paul, of France, underwent the same cruel lot. Happily for the world, he escaped from slavery, to commence at home that long career of charity--nobler than any glories of literature--signalized by various Christian efforts, against duels, for peace, for the poor, and in every field of humanity--by which he is placed among the great names of Christendom. Princes and orators have lavished panegyrics upon this fugitive slave; and the Catholic Church, in homage to his extraordinary virtues, has introduced him into the company of saints. Nor is he the only illustrious Frenchman who has felt the yoke of slavery. Almost within our own day, Arago, the astronomer and philosopher,--devoted republican, I may add also,--while engaged, early in life, in those scientific labors, on the coast of the Mediterranean, which made the beginning of his fame, fell a prey to Algerine slave dealers. What science and the world have gained by his emancipation I need not say.