Answer:
   
   The Bahir is one of the oldest and most important of all Kabbalistic
   texts. Until the publication of the Zohar, the Bahir was the most
   influential source of Kabbalistic teachings. It is quoted in virtually
   every major Kabbalistic work and is cited numerous times by the Ramban
   in his commentary on the Torah. It is also paraphrased and quoted many
   times in the Zohar.
   
   The name 'Bahir' literally means 'brilliant' or 'Illumination', and is
   derived from the first verse quoted in the text of the Bahir "And now
   they do not see the light, it is brilliant [bahir] in the skies",
   which itself is a quote from the book of Job (37:21).
   
   This book is also called "The Midrash of Rabbi Nehuniah ben haKana".
   Although the Bahir is a fairly small book, 12,000 words in all, it was
   very highly esteemed. It was first published in Provence in 1176. Most
   Kabbalists ascribe authorship to Rabbi Nehuniah ben haKana, a Talmudic
   sage of the first century.
   
   One of the most important concepts revealed in it is that of the ten
   Sefirot. Also discussed are the opening verses of Genesis and their
   true meaning; The mystical aspects of the Hebrew alphabet; A
   discussion of Gilgul [reincarnation]; The 32 paths of Wisdom, and the
   Tzimtum, among other topics.