The first rabbinical epoch was fertile in original minds, also producing a character whose course tended to shake violently the firm basis of Judaism. Abu Ibraham Isaac Ibn-Kastar (or Saktar) ben Yasus, with the literary title Yizchaki, was a man whose profound knowledge of philosophy and medicine was also celebrated among the Arabs. Born at Toledo (982, died 1057), he was appointed physician to Mujahid, the Prince of Denia, and his son Ali Ikbal Addaula. Ben Yasus composed a Hebrew grammar, under the name of "Compositions," and another work with the title of "Sefer Yizchaki," in which he displayed remarkable boldness in his Biblical explanations. He asserted especially that the portion of the Pentateuch in Genesis which treats of the kings of Edom was not written by Moses, but was interpolated some centuries later, a critical statement unique in the Middle Ages, and not advanced until very recently. It would be wrong to pass over in silence a poet, who, for flight of fancy, depth of thought, and beauty of expression, may claim equality with Solomon Ibn-Gebirol, but of whose poems only a single one is extant, "an orphaned song," as he himself called it. Abu Amr Joseph ben Chasdaï was probably born in Cordova. His two brothers, who were compelled by the troubles of the wars in Spain to leave home, dwelt under the protection of the statesman, Samuel Ibn-Nagrela. Respect and thankfulness towards their noble patron induced Joseph ben Chasdaï to write an elevated, artistic, and highly imaginative poem, in which he eulogized Samuel and his young son Joseph with enthusiastic warmth (about 1044-1046). Samuel, who would never accept anything, not even a gift of praise, without making some return, wrote, in praise of Joseph ben Chasdaï, a similar poem in the same meter, but not possessing the same poetical beauty. Joseph ben Chasdaï left a son, who later obtained in Saragossa a position similar to that of Ibn-Nagrela in Granada. Samuel, the pride of the Spanish Jews, who, as his biographer says, bore four crowns, the crown of the Law, of the priesthood, of renown, and pre-eminently that of magnanimity, was the soul of the Jewish congregation for over a quarter of a century, and died deeply lamented by his contemporaries (1055). He was buried at the gate of Elvira, in Granada, and his son erected a magnificent monument to him. A still finer monument was built for him by Solomon Ibn-Gebirol in a few pregnant lines: "Thy home is now within my heart, Whence ne'er shall thy firm tent depart. There I seek thee, there I find thee, Near as my soul art thou to me."