For the last six years, Joel Hecker, an associate professor at the Reconstructionist Rabbinical College in Wyncote, has pored over a set of medieval writings to help unlock one of the most important texts in Judaism.

Hecker, 56, of Bala Cynwyd, has dissected centuries-old manuscripts and translated hundreds of pages of Aramaic to contribute to a new English translation of the Zohar, a compendium of commentaries and essays that is the foundation of the Jewish mystical tradition known as Kabbalah.

In its 20th year, the landmark project will produce the first unabridged translation, with commentary, that is based on the 13th-century text's original Aramaic, a Semitic language that emerged nearly 3,000 years ago and is now little spoken in the Middle East. Expected to be completed next spring, the 12-volume work of more than 6,000 pages will take an esoteric, complicated text out of the domain of scholars and Jewish mystics and make it accessible to a wide, modern audience.

The Zohar: Pritzker Edition, funded by a $2 million donation from one of the nation's wealthiest families, is what Hecker calls a definitive and comprehensive "field guide" to the Torah. Its purpose is to illuminate what the Torah says about the mysterious relationship between God and his creation.

Ten volumes already have been published, by Stanford University Press. The 11th - part of Hecker's work - is scheduled for release Wednesday, between the High Holy Days of Rosh Hashanah, beginning at sundown Sunday, and Yom Kippur on Oct. 11.

Unlike earlier English translations, the Pritzker Edition does not include paraphrases, abbreviations, or deletions of text, Hecker said, nor has it been converted from a Hebrew translation.

"The whole project is extremely important because it's the first full rendering in competent English that incorporates the highest standards of scholarship in the field," said Elliot R. Wolfson, a leading expert in Jewish mysticism and a professor of Jewish studies at the University of California, Santa Barbara.

Hecker, who trained as a rabbi and later studied for his doctorate under Wolfson, is part of the translation team led by Daniel C. Matt, a Kabbalah scholar and former professor at Graduate Theological Union seminary in Berkeley, Calif.

Matt began translating Volumes 1 through 9 in 1997. He selected Hecker and Nathan Wolski, of the Australian Centre for Jewish Civilization at Monash University, in Victoria, Australia, to join the project in 2010 and help complete it.

Hecker's Volume 11 contains commentaries on the Song of Songs (also known as the Song of Solomon) and the Books of Ruth and Lamentations. He and Wolski collaborated on Volume 12, which has discussions of the ancient and medieval practice of deducing character traits from hands and facial features.

The Zohar was first distributed by the Jewish mystic Moses ben Shem-Tov de Leon in 1280 and 1290. De Leon handed out the writings in pamphlet form in Castille, present-day Spain, claiming they had been kept secret for more than 1,000 years and had been authored in the second century by Rabbi Shim'on bar Yohai, a famed scholar from ancient Israel.

In the Zohar, Rabbi Shim'on and his companions travel through the hills of Galilee, where they discover and share the secrets of the Torah. God is portrayed not only as a distant deity who lays down rules and commandments, but as a knowable creator with characteristics that are both male and female, Hecker said.

"It opens up a whole new universe of what Judaism might be about," Hecker said.

The writings have been translated into Hebrew, Latin, German, and French. Earlier English translations include a five-volume version published between 1931 and 1934 by the Soncino Press in Italy.

In 2003, the controversial Kabbalah Centre in Los Angeles - cofounded by Rabbi Philip Berg, who tutored such celebrity followers as Madonna - published a 23-volume translation based on an earlier Hebrew translation, not the original Aramaic, Matt said.

Enter Chicago philanthropist Margot Pritzker, who had studied Judaism for years with Rabbi Yehiel Poupko, a rabbinic scholar with the Jewish Federation of Metropolitan Chicago.

In the mid-1990s, Poupko and Pritzker, who has a master's degree in Hebrew Bible, were using the Soncino Press version during class sessions. Pritzker described the text as "lacking" and the experience as "frustrating."

The 1930s translation did not have the benefit of the "significant scholarship" that has occurred since then, Poupko said.

He suggested to Pritzker that she sponsor a translation.

"I said, 'Let's do it,' " Pritzker recounted.

Pritzker and Poupko sought out Matt.

Initially reluctant to take on a project that he figured would last 12 to 15 years, he eventually agreed to shoulder it. He left his job at Graduate Theological Union. The first of his nine volumes was published in 2003.

When project leaders decided they wanted to finish the translation by 2016, Matt selected Hecker and Wolski to join the team.

"I was so thrilled . . . ," Hecker said. "I have little doubt this will be one of the highlights of my scholarly career, and probably the most lasting."

Volume 12 is in final editing.

Wolfson's only critique of the work so far is that the translators have not included a listing of the scholarly manuscripts they have used.

Hecker says that will eventually appear online.

Next month, Matt will lead presentations on the translation at the Germantown Jewish Centre in Mount Airy, where he is scheduled to be a scholar in residence Nov. 10-13.

"This is a gift to scholarship, to Western civilization that unlocks a secret," Poupko said. "No one could read it - only a few scholars and mystic initiates. Now, everyone can pick it up and read it for the first time.