The famous kabbalistic SEFER HA’BAHIR-THE BAHIR was first published in France (Provence) around 1176. The majority of Kabbalists claims that the author of “The Bahir” is the Talmudic Rabbi Nechunia ben HaKana from the first century. A former student of Rabbi Yochanan ben Zakkai.
When I say the book was “published” it basically means that it was only accessible to a limited amount of Kabbalistic circles. In those days, books were not available as printed editions but only as handwritten manuscripts.
Rabbi Aryeh Kaplan states that, until the ZOHAR was published in 1290, Sefer HaBahir was the most important kabbalistic writing. However, Rabbi Shimon bar Yochai (most Rabbis claim that he was the author of the Zohar and not Rabbi Moshe de Leon in 1290) was familiar with Rabbi Nechunia ben HaKana’s teachings.
Sefer HaBahir introduces, among other subjects, the concept of TZIMTZUM. Before G-d created the universe, it was Him existing alone. He filled out a space. It was only Him existing and NOTHING or NOBODY else. Not even darkness or a space but ONLY G-d.
In order to make Creation possible, G-d had to make a void. In order to do this He had to contract Himself in order to make space for something else: Our Universe and all Existence.
G-d withdrew His light in order to form a vacated space where Creation would take place. The Tzimtzum concept became extremely famous through Rabbi Yitzchak Luria (the Arizal). However, he didn’t invent the Tzimtzum but what he did invent were the Partzufim.
Everyone should be aware that the Tzimtzum concept is not to be taken literally but only a metaphor in order to get an idea of how the Creation process may have taken place. Kabbalistic literature speaks in symbols and metaphors.