 The first traces of al-Kindi’s influence have been found in Jacob al-Qirqisani, a Karaite Jewish author living in Mesopotamia (where al-Kindi himself was living one century before) in the first half of the 10th century. In al-Qirqisani’s main published non-philosophical work, the Book On the Lights and On the Guard Towers (Kitab al-anwar wa-l-maraqib), a study of the legal parts of the Pentateuch, Georges Vajda identified some passages of al-Kindi’s Epistle On the Quiddity of the Sleep and the Vision (Risala fi mahiyya al-nawm wa-l-ru’ya), who al-Qirqisani would have employed for his description of the concept of “sleep” (Vajda 1941–1945, 115–122). Other traces of a philosophical work by al-Kindi, his Epistle On the Cause Producing Ebb and Flow (Risala fi l-‘illa al-fa‘ila li-l-madd wa-l-jazr), have been found by Bruno Chiesa in a passage about the world’s creation in al-Qirqisani’s most important (and still unpublished) theological-philosophical work, the Book of Gardens (Kitab al-riyad), a study of the non-legal parts of the Pentateuch (Chiesa 1989, 95). Of course, a complete analysis of al-Qirqisani’s own “philosophy”, as found in the latter work, is still needed, so that the real force of al-Kindi’s influence on his thought can be evaluated.