Spanish cabalist of the end of the thirteenth century; born at Soria; buried at Segovia; also called Gikatilla, according to Jellinek ("Beiträge zur Gesch. der Kabbala," 2:49). The cabalist Isaac ha-Kohen of Béziers was his elder brother, and outlived him. Nothing definite is known regarding Jacob's life. Of his works only "Tefillat R. Ya'aḳob mi-Seguba," a cabalistic prayer, has been printed (in Gabriel Warschauer's "Liḳḳuṭim me-Rab Hai Gaon"). His most important work is "Perush Ẓurot ha-Otiyyot," on the form of the letters of the Hebrew alphabet.