Isaac Casaubon (1559-1614), one of the greatest scholars of the late Renaissance, is hardly remembered today. In his time, though, this son of French Calvinist refugees living in Geneva was regarded by some as “the most learned man in Europe.” He held positions as professor of Hebrew in Geneva and Montpelier, was a librarian to the king of France, and ended his life in Oxford, England, as a personal friend of King James I and a friend by correspondence of all the leading members of the early 17th-century Republic of Letters.Best known for his philological expertise in Greek and Latin, Casaubon translated (into Latin) some major Greek literary, historical and philosophical texts and established critical editions of others. His philological sensitivity also enabled him to expose several ancient texts as forgeries, most notably the celebrated Corpus Hermeticum – a collection of mystical Greek texts believed to have been written by Hermes Trismegistus, an Egyptian priest and prophet and a contemporary of Moses who had allegedly unveiled the secrets of Christianity.Casaubon lived during an unprecedented revival of interest in the Hebrew language among Christian scholars in Europe. Admittedly, Renaissance humanists in Florence and elsewhere had already pursued Hebrew and Aramaic kabbalistic texts, hoping to find in them keys to the mysteries of the divine. But the conflicts between Catholics and Protestants in the 16th and 17th centuries pulled the study of Hebrew from esoteric to mainstream scholarship. Scripture, Luther declared, was the key to salvation, and reading it in Hebrew was the safest way to get its meaning right. Protestant universities established professorships of Hebrew, while Hebrew grammars, dictionaries and lexica were rushed out of printing presses. Some of these were composed by non-Jewish scholars, but most were by Jewish grammarians, such as Rabbi David Kimhi (Radak).Equally important was that the rabbis, including talmudic ones who, in the Middle Ages, had been accused of blindness to the truth and defense of deicide (the crucifixion of Christ), now enjoyed their moment in the sun. While their teachings were all wrong, the argument went, they still had preserved extensive knowledge of Jewish religious practices and beliefs from the time of Jesus. As such, there was much to learn from them in order to reach a better understanding of the words and deeds of Christ and his followers, and thus to win souls in the inter-Christian debate. Thus, the Talmud (earlier banned and burned) was now translated into Latin, as were exegeses by Maimonides, Nahmanides, Abraham Ibn Ezra, Rabbi Shlomo Yitzhaki (Rashi) and more recent authors such as Isaac Abravanel. Christian Hebraism was all the vogue for a short while, as were, to a much lesser degree, Christian Chaldeanism (the study of Aramaic), Christian Arabism and Christian Yiddishism (the latter recently rediscovered by the young Israeli scholar Aya Lahav-Elyada).Casaubon never published any book on Hebrew or Jewish topics. But Anthony Grafton and Joanna Weinberg, two eminent historians of Renaissance scholarship, convincingly make the case in their fascinating and gorgeously produced book I Have Always Loved the Holy Tongue that he was nonetheless an industrious Hebraist whose study of and familiarity with Hebrew should be added to his outstanding achievements in Greek and Latin scholarship.Due to the lack of any Hebrew book bearing Casaubon’s name, Grafton and Weinberg worked as detectives. They sifted through piles of books and manuscripts in libraries, read Casaubon’s 3,000 letters and massive diaries, and searched for books annotated in his hand. His Hebrew marginalia, much of it reproduced in the book in beautiful photographs, is written in big square letters and reads almost as if it were print. Casaubon read the Mishna, the Talmud and the Zohar, but also the above-mentioned authors, as well the Hebrew Jossipon (a 10th-century Jewish chronicle thought to have been written by Josephus Flavius), Sefer Hassidim, Abraham Zacuto’s Sefer Hayuhasin, and even Yiddish homilies, as well as a Yiddish version of the Shulhan Aruch.He used much of his reading to criticize a recent Catholic official version of the life of Jesus and the early Church.There is little sympathy for the Jewish faith or for Jews, least of all for the rabbis, in Casaubon’s annotations (even though he seems to have played a role in saving a Jew from public burning in 1613). According to him, “Christians should pay attention to rabbis only when they speak about the Hebrew language, institutions, or the calendar; but when it comes to history or the explication of the antiquities of the Jewish people or their covenant with God, no confidence should be given to their testimony.”Along the way, however, it seems that Casaubon fell in love with the Holy Tongue, as he wrote to a friend. Through the thick layers of pedantry and anti-Catholic polemics, one gets a sense of Casaubon’s sheer delight in reading Hebrew texts, deciphering roots of words, and, above all, catching colleagues’ mistakes (not much has changed in the Republic of Letters). In their love for both the subject matter and the protagonist of their book, and their pleasure in the detective work, Grafton and Weinberg bring Casaubon’s own joy to life.The authors admit that Casaubon was only a second-tier Hebraist. But his use of Hebrew illuminates the contribution of people like him not to philology per se, but to a revolution in theology and historiography. He was, they rightly point out, one of the first to realize the (currently self-evident) view that a better understanding of Second Temple Judaism, early Christianity and late Hellenism cannot be achieved without a thorough familiarity with, and respect for, all religious cultures and all languages of the period.