The national poetry of Jehuda Halevi is of higher value, since it has its source not in mere poetical sentiments, but in earnest and impassioned conviction. He was not only the perfect poet, he was also the brilliant thinker; in him feeling and thought were completely blended. Poetry and philosophy were intimately united within him, neither being strange, borrowed, or artificially acquired, but each being an innate possession. Just as he gave expression to the national feelings of Israel in his songs of Zion, so he interpreted, if one may say so, the national thoughts of Judaism in an ingenious and spiritual manner. Poetry and philosophy were employed by him only to glorify and spiritualize the inheritance of Israel. He propounded original ideas on the relation of God and the world, of man to his Creator, on the value of metaphysical speculation, of its connection with Judaism, and on the importance of this religion as contrasted with Christianity and Islam. All these problems he solved not in a dry, scholastic fashion, but in a lively, interesting, and convincing manner. If in his lyrics we may liken him to a son of Korah, in the development of his thoughts he resembles the author of Job, but he is richer in matter, more profound, more comprehensive. From Job or from Plato, Jehuda Halevi borrowed the form in which his religious philosophical system is presented. He expounds his thoughts in the form of a dialogue, and like the author of Job, combines them with an historic fact, thus giving more intense interest to the theme, and conveying a lasting impression. When certain of his disciples asked him how he could defend rabbinical Judaism, and how reply to the objections hurled against it by philosophy, Christianity, Islam and the Karaites, he produced his answer in a comprehensive, erudite work in the form of a dialogue written in elegant Arabic. As its title denotes, the book was intended to demonstrate the truth of Judaism and to justify the despised religion. A heathen, who knew nothing of the wisdom of the schoolmen, nor of the three existing religions, but who felt the necessity of uniting himself in a spiritual, affectionate union with his Creator, becomes convinced of the truth of Judaism. This heathen is Bulan, the king of the Chazars, who himself embraced the Jewish faith. Him the Castilian philosopher makes use of to give an historical character to his work, and hence it bears the name of Chozari (wrongly spelt Kusari). The clever preface, written in an appropriate style, stirs the interest of the reader.