Calendars are always complicated and sometimes baffling. Layered with history and ritual, they bind communities together by preserving traditions and erasing the passage of time. My father taught me to observe Passover as if I had been a slave in Egypt: to imagine that I had dragged stones up pyramids and then followed Moses to freedom. Hearing his powerful voice and evocative words, I could see the Exodus, once a year, in my mind’s eye. Yet time does pass, and as it passes traditional calendars develop fissures and contradictions. The long Seder my family celebrated, reclining at table, did not much resemble the Passover prescribed in Exodus 12:11: “And thus shall ye eat it, your loins girded, your shoes on your feet, and your staff in your hand; and ye shall eat it in haste.” The Jewish calendar as a whole, with its year count and months that did not match the standard ones, was a mystery to me. It was even more confusing to realize, as a child, that it must have changed in multiple ways since ancient times.If you’ve ever wondered about the Jewish year and its history, Elisheva Carlebach’s marvelous new book, Palaces of Time: Jewish Calendar and Culture in Early Modern Europe, has much to offer you. A preeminent specialist on the Jews of early modern Germany, Carlebach concentrates on what became of the calendar in the early modern period. In the 16th century and after, technical literature about time, which had once been treated as an esoteric knowledge reserved for an elite, became widely available to Jews for the first time, and Carlebach traces this process in detail. But as she reaches back to explain the distant origins of early modern debates and practices and sets the calendars into their larger contexts, Palaces of Time provides even more than it promises: a fascinating and provocative introduction, full of surprises, to the Jewish experience of time.Richly documented and sumptuously illustrated, the book tells a sinuous and sometimes wild story, one in which books of many kinds, in all their grubby materiality, play central roles. Carlebach has long been known as a supremely skillful reader of texts—an approach long central to Jewish scholarship, and one sometimes combined with a reluctance to admit that readers actually encounter texts in the material form of books, where they often leave rich evidence about these encounters. From the 1970s on, historians of the book—Robert Darnton, Lisa Jardine, William Sherman—have shown how to enrich intellectual history by combining textual analysis with the study of books as material objects. Malachi Beit-Arie, Adam Shear, and others have successfully applied this method to Jewish texts. Carlebach too now attends, with great skill and sensitivity, to the material forms of the books she studies, to their sometimes-cheap paper and poor print, their complex and powerful illustrations, and their annotations. Reading in this new way, she can tell us not only what the calendar texts say, but what mattered most in them to the Jewish readers and thinkers who printed them, and copied them, and annotated them, and wore them out.In the 15th century and after, Jews produced calendars of every kind, from simple wall charts listing feasts for the year to come to ibburim and sifre evronot, technical treatises on the structure and meaning of the year and longer cycles. Like the rabbinic Bible and the Talmud, Hebrew works on the calendar were printed and reprinted, not only by Jews but also by Christians. Johann Froben, the great Basel printer who was Erasmus’ chief publisher for much of his life, brought out the first printed ibbur in 1527.Yet calendars also continued to circulate in manuscript form for centuries. Printed calendars and treatises often swarmed with typographical and technical errors, as press correctors noted when they produced what they claimed were better editions. Mistakes piled on mistakes could make these technical works too inaccurate to use. A careful reader—like the two portrayed on a page from a Berlin manuscript reproduced by Carlebach, studying their sifre evronot on opposite sides of a table—might well prefer to make his own copy, especially if he could use a sefer yashan noshan (very old book) as his model. In the wake of ritual murder trials, efforts to ban the Talmud, and expulsions of ancient Jewish communities, scholarly Jews in the German world feared that their traditions might disappear. They transcribed ancient treatises on the calendar as zealously as ancient works of Kabbalah. The literature of time spanned a spectrum from smudgy single sheets, mechanically reproduced and swarming with errors, meant to be nailed to the walls of shops and hovels, to quaint and curious volumes of forgotten lore, treasured by the learned bibliophiles who had copied them.Carlebach emphasizes the learning of the Jews in Frankfurt and other centers. But no one, not even the most erudite scholar, could master all the mysteries of the Jewish calendar and its development in this period. The Jewish calendar tries—like other calendars—to square the circle. It follows both the motion of the sun, which passes through the zodiac, determining the seasons, in 365 and one quarter days, and that of the moon, which does the same in 29 and a half days, defining the months. The solar year isn’t evenly divisible into lunar months: how then to know when each Jewish month should begin? In the early centuries of the Common Era, Jews relied on direct observation. Once two independent, sober witnesses had given formal notice that they had observed the new moon, the Sanhedrin would declare that the month had begun and send out messengers with the news. But this system had obvious disadvantages, especially for Jews who lived in the Diaspora. Worse still, because the lunar year was only 354 days long, its months drifted forward in the seasons. Nisan, which is supposed to be the first month of spring, moved into winter. From time to time, accordingly, the Sanhedrin had to intercalate another month, to ensure that Passover took place, as it should, in the spring.From the 4th century onward, the Jews of Babylon—where astronomy had been practiced in a sophisticated way for many centuries—reconfigured their calendar. An astronomical cycle, 19 years long, at the end of which the lunar and solar years coincided, determined when to add intercalary months. This fixed calendar, traditionally associated with Hillel II, found widespread acceptance. But it was challenged by the Qaraites, who insisted that the calendar, like all other Jewish practices, must rest on the Bible alone. And it provoked fierce debates in the 10th century, when Palestinian and Babylonian communities celebrated Passover on different days.Two Jews, four calendars. In the 11th and 12th centuries, Jews mastered the new astronomy of the Muslim world. But if Maimonides and Ibn Ezra agreed that these shiny new tools should be put to work perfecting the Jewish calendar, bar Hiyya denounced them and insisted that the astronomy of the patriarchs and ancient rabbis had been more accurate. Only inklings of these fierce arguments—and of the issues they had turned on—found their way into the calendrical texts that were actually printed or copied in Renaissance Europe, and that “winnowed, diluted and mediated the mass of material for the common reader,” Carlebach writes. The great Christian student of calendars Joseph Scaliger may well have been right to proclaim that most 16th-century Jews believed that their fixed calendar went back to Moses himself.For all their lack of concrete historical information about the Jewish year, the calendrical texts were richly stocked with other materials. Under Carlebach’s skillful hands they yield a flood of new information about Jewish life and thought. Manuscript sifre evronot were often richly and imaginatively executed. Carlebach reproduces many pages, which she explicates with great skill. Like astronomical writers in the Islamic and Christian worlds, Jewish calendar experts equipped texts with volvelles: dials made of layered paper rings, precisely marked off, which could be used to speed up computations. The calendrical works that included these were little analog computers made of paper.Like Christian illuminators, Jewish ones introduced a rich vein of visual fantasy into many technical books. At the chart for checking one’s calculations, known as a panim ahor (face-back), manuscripts show a man standing on his head or displaying his bare backside to the reader. Puns and plays on words are common. To illustrate the new moon, for example, the illuminator might show a mother rocking her baby in the crib (molad, the technical term for new moon, literally means birth).Sometimes the symbols are more than idle fantasies. Christian books of hours, designed to help laymen perform their daily devotions, often contained elaborate illustrations of hunts. So did sifre evronot. Mounted and on foot, armed with spears and guns, well-dressed hunters pursued tags and hares, boars and birds across the pages of these technical, largely quantitative books. Sometimes the hunted animal escaped. Pinhas of Halberstadt, in the 18th century, copied hunting scenes directly from Christian models. As their captions he inscribed verses from Isaiah that evoked the eventual triumph of the Jews. For Christians riffling the pages of their prayer books, a hunted hare was just a hare. For Jews reading their calendars, the hare became an emblem of their hope for survival among hostile nations. The calendar really could be a palace of time—or at least a pleasure garden, where Jews found a real if limited refuge from the humiliations and terrors of everyday life in a persecuting society.The calendars illuminate rituals as well as feelings. In order to establish the astronomical basis of the Jewish year, ibburim explained how to compute the exact times of the tequfot (equinoxes and solstices, the turning points of the sun). Often writers glossed the computations with elaborate warning statements. Water and other liquids must not be left uncovered at the moments when the sun passed the equator or the tropic of Cancer or Capricorn, since they would become corrupt or even turn to blood. Fortunately, covering them—and placing a nail or other piece of iron in them—would prevent harm.Though these beliefs and practices came into existence by the time of the Geonim, in the second half of the first millennium CE, they never won universal acceptance. Ibn Ezra denounced them as mere superstition. After all, he argued, Jews had not yet mastered the Muslim methods that would let them determine when the equinox actually took place. How then could they possibly predict its effects on beverages? As late as the 18th century, though, Jewish converts to Christianity told stories of the blood that had appeared in uncovered goose fat at the tequfah and of the old woman who drank sweet milk infected at the tequfah with blood, not all of which she managed to skim off, and died, hideously swollen, her flesh falling from her body. These accounts, Carlebach argues, show that covering liquids at the tequfah was women’s work, carried out with real urgency and sometimes—if the reports deserve belief—accompanied by strikingly high anxiety.Calendars and calendar treatises often crossed borders. From early in the common era, after all, Jews and Christians established their distinctive ways of infusing time with sacred meaning: the Jewish Sabbath and the Christian Sunday, Passover and Easter. But the only way to ensure that one had avoided serious errors in ritual was to know the enemy, or at least the enemy’s way of ordering time. From the Venerable Bede on, Christian experts on the ecclesiastical calendar took care to learn about the Jewish holidays as well. Otherwise, they explained, one might find oneself celebrating Easter at the wrong time, while the Jews mocked.The first ibbur to reach print was edited, in Hebrew and partial Latin translation, by a Franciscan expert on calendars, Sebastian Münster. One of the most visually striking features of Münster’s edition is a standard Catholic calendar in Latin, bristling with saints’ days—and with the names of the Jewish months, printed in Hebrew, each of them entered in the margin at the day where it began. No philo-Semite, Münster took care to explain that he presented this material to the Christian reader “not because I wish to instill Christian minds with Jewish rituals, but because I know that knowledge of them is vital for the Old Testament and Hebrew commentaries.” Without such knowledge no one could hope to read the rabbis, who frequently mentioned Jewish festivals. Later Protestant calendars drawn up by the Wittenberg astronomer Paul Eber omitted the saints’ days but entered the names of the Jewish months, which they treated as identical to the Christian ones, and identified Jewish holidays and great events in the history of the ancient Jews—as well as the Greeks and Romans—that had fallen on each day through the year. Not all Christian calendars, but many Protestant ones, were partially Judaized.Jewish calendars also offered information about their Christian counterparts. Jews often knew the rhythms of Christian time better than they wanted to, since holy days provided the occasion for hostile acts that ranged from mocking plays to ritual slapping or stoning. Rabbinic tradition, moreover, forbade Jews to trade with Christians for three days before or after a Christian feast—or at least on the feast days themselves. But Christian market fairs often took place on or near holy days. And Jews who engaged in trade had to know when the fairs would be held in order to attend them—and, if all went well, to enjoy the fragile, temporary freedom and openness in dealing with others, Jewish and Christian alike, unknown in their ordinary lives at home, that the liminal world of the fair might allow. Jewish calendars that marked Christian holy days could be signaling the possibility of danger. But they might also be pointing to something very different, Carlebach writes: “If Jewish life in premodern times sometimes felt like a stifling enclosure, markets and fairs served as windows, allowing fresh ideas and impressions in, and allowing non-Jews to look in at the Jewish culture through a lens that was far less distorting.”Calendars—as Carlebach makes clear—offered information not only about the passage of time through the year but also about time in the long term—historical time. Feasts, fasts, and particular dates recalled events that ranged from biblical times to the recent past and from cosmic to purely local importance. Calendars were as likely to remind readers of the day when Noah first saw the peaks of the mountains rise above the waters of the Flood as of the day when the Jews of Frankfurt were expelled from the city. Short chronicles—Carlebach calls them “chronographs”—often appeared with sifre evronot, listing the intervals of years from the Creation to the great events of biblical history and then down to more recent times, and noting sabbatical and Jubilee years. Fixed and uniform in their vision of the ancient past, chronographs were flexible and expansive where more recent times were concerned. Calendars not only guided Jews through the year but also fixed—and then revised—their shared, distinctive visions of history.These visions were often charged with secret and powerful messages. In antiquity, the Jews, like other Near Eastern peoples, had devised a form of history capable of tracing time from its beginning and revealing the deeper, theological meaning of events. Prophetic writers searched the past for patterns that could reveal the course of history as a whole, the future as well as the past. Apocalyptic texts often contained chronologies that revealed—in, for example, the book of Daniel—when the Messiah would come. The chronographs in Renaissance calendars reflect these visions of time and its course. Christian calendars sometimes predicted great events and disasters on the basis of conjunctions of the planets: for example, the great conjunction in Pisces in 1524, which many thought heralded a second universal Flood. Jewish calendars, by contrast, highlighted numerical patterns that seemed to reveal the divine plan, Carlebach explains: “A calendar for 1738-1739 used an eschatological chronogram for the anno mundi year 499: yifdeh (He will redeem).” Calendars from the mid-17th century, when many accepted the messianic claims of Sabbatai Zevi, connected the year 5426 (1665-1666) with the prophetic words “Behold I will save [Hebrew: moshi’a],” since the numerical value of moshi’a is 5426. Even the most modest little calendar might offer the secrets of life, the universe, and everything—or at last the date when time itself would run out.Palaces of Time finds its ending in the age of emancipation and the 19th-century Wissenschaft des Judentums, when influential Jews like Leopold Zunz, a founder of the Wissenschaft, began to date events by the Gregorian calendar and when actual calendars were reduced to technical appendixes in almanacs that featured all sorts of other useful information. In a way, this is a pity. A final chapter on Jewish time in the varied social worlds of contemporary Israel, from Mea Shearim to the Technion, could have revealed a great deal about the afterlife of the structures that Carlebach rebuilds here with such scholarly craftsmanship.Carlebach could also have asked at least one more comparative question. In On Time, Punctuality, and Discipline in Early Modern Calvinism, the Swiss scholar Max Engammare argued that the calendars produced by Reformed scholars, which encouraged readers to plan their days and their weeks, helped to instill in the Swiss their legendary regard for punctuality. What impact, if any, did Jewish calendars have on the day-to-day behavior of their owners? In virtually every other respect, though, the book is exemplary. Palaces of Time is cultural history at its finest: a minutely observant, vivid, and passionately enthusiastic guide book to a world of experience that we—or at least most of us—have lost.