But the beginning of the manuscript was missing, and Saphir's statement that the author's name was Isaiah and that the title was Al-Nur wal-Zulm depends only upon hearsay.
Two other manuscripts, one in Berlin[2] and one in the Bodleian Library,[3] bear the author's name, Nethanel ben Isaiah, and the full title of the work, Nur al-Zulm wa-Mashbah al-Hikm wa-Ikhraj al-Ma'ani fi al-Wujud Ba'd al'Adm.
Alexander Kohut published a monograph on this work, giving some extracts, under the title "Light of Shade and Lamp of Wisdom" (New York, 1894).
He inserted in his work three Hebrew poems, two of which were published by Kohut in his above-mentioned "Light of Shade and Lamp of Wisdom."
Nethanel is often quoted under the designation of "ibn Yesha'yah" by Mansur al-Dhamari and by Daud al-Lawani in his philosophical commentary on the Pentateuch entitled al-Wajiz al-Mujna.