Member of the embassy sent in 797 by Charlemagne to Harun al-Rashid, calif at Bagdad, probably as interpreter for the ambassadors, who were the noblemen Sigismund and Landfried. Both died on their way back, and Isaac became the sole bearer of the calif's answer and presents, among which latter was a magnificent elephant. When the emperor was informed of Isaac's return to France, he sent the notary Erchenbald to Liguria in order to prepare for the transportation of the elephant and the other presents. Isaac arrived at the port of Vendres in Oct., 801; but, as the Alps were covered with snow, he was obliged to pass the winter at Verceil. He reached Aix-la-Chapelle in the summer of 802, and the emperor received him in audience there.
Zunz ("G. S." i. 157) supposes that Isaac was the means of establishing relations between the French rabbis and the Geonim, as France is not mentioned in the decisions of the latter before 850 ("Sha'are Ẓedeḳ," p. 12).
- Eginhard, Annales, pp. 51, 52, in Guizot's Collection des Memoires, vol. iii., Paris, 1824;
- Grätz, Gesch. 3d ed., v. 184-185;
- Steinschneider, Jewish Literature, p. 81;
- Aronius, Regesten, No. 68.