though an incorrect ritual decision would rouse him to indignant energy. He carried on a controversy with several rabbis concerning the legal status of a betrothed girl who had been forced by circumstances to adopt Christianity and had afterward returned to Judaism. His anxiety for correct observance led him to counsel the more difficult rather than the easier ritual practise. His mystical studies account for his belief in miracles. He was held in high regard by his pupils, and, like other teachers of the time, was given the title Ha-Kadosh ("the holy", by the Rosh). His contemporary Isaiah di Trani described him as "the wonder of the age". Bibliography from Jewish Encyclopedia article S. N. Bernstein, in Ha-Ẓefirah, 1902, Nos. 229, 231, 232; Heinrich Grätz, Gesch. vii.101; Gross, in Monatsschrift, 1871, pp. 248 et seq.; Moritz Güdemann, Gesch. i.114, 152, 153; Leopold Zunz, Z.G. Index; idem, in Moritz Steinschneider, Hebr. Bibl. 1865, pp. 1 et seq.; idem, G.S. iii.128 et seq.; Weiss, Dor, v.73 References External links Who Was Isaac of Vienna? by Dr. Henry Abramson 13th-century Austrian rabbis 13th-century Bohemian rabbis Austrian Orthodox rabbis Rabbis from Vienna Czech Orthodox rabbis 1200 births 1270 deaths Authors of books on Jewish law