The Tree of Life diagram is based on the seven branched candelabrum known as the Menorah from the Biblical Book of Exodus (35:21-35). The menorah was made out of one piece of gold smelted from the treasures the Israelites brought with them from Egypt.
It was built to a design precisely described in Exodus and placed in the tabernacle of the moveable temple built by Moses and the Israelites in the wilderness. It has been referred to by mystics through the centuries as the source of the oral Torah (Law); the first five books of the Bible and its design and markings represent the Sefirot, the paths and the four different worlds or levels in Kabbalistic teaching.
The first written correspondences between the Menorah and the Tree of Life were outlined by the early Christian Church Father Iraneus, and later by the 18th century mystic Rabbi Moshe Chaim Luzzato. The concept was further developed by the 20th/21st century father of Toledano Kabbalah, Z’ev ben Shimon Halevi.
The Tree of Life design as we know it today is believed to have been adapted from the design of the Menorah by Rabbi Yizhak Saggi Nehor (1160-1235) who was known as Isaac the Blind. The Rabbi or his students are also credited with clarifying Kabbalistic teaching on reincarnation and Karma and naming the Sefirot.
Rabbi Isaac believed that contemplating the aspects of the Sefirot with sacred intention, known as Kavana, could bring people into direct contact with divinity.