Classical Kabbalah: little is known about Kabbalah in ancient times, because of course there were no written records. However, by medieval times, when parts of the Kabbalah were written down for the first time, it had developed into three recognizable strands: Contemplative Kabbalah, Mystical Kabbalah and Practical Kabbalah.

Contemplative Kabbalah: by its very nature, this is the aspect covered by most written works on Kabbalah; it is, so to speak, the "thinking man's Kabbalah". Much of this branch of Kabbalah grew out of the study of the Holy scriptures. Various techniques of extracting the underlying meaning of the Holy texts were devised: Gematria, Notariqon and Temurah, devices based on the resonance of numbers and letters, were among them. Theories of how the Universe was created, and of the essential nature of man, were devised and elaborated, theories that could be summarized and epitomized in the potent glyph that we know as the Tree of Life.

Mystical Kabbalah: also known as Merkavah (Chariot) Kabbalah, the mystic sought direct contact with the divine essence through spiritual experience. In a meditative state, the soul would be carried away to Heaven in a Chariot-like vehicle. Several of the Prophets of the Old Testament record unmistakable descriptions of the Merkavah experience. In this Russian icon, Elijah is taken up into Heaven in a Chariot of Fire.

Practical Kabbalah: many would call this "magic", but it was actually a theurgic practice designed to bring about the practical effects desired by the operative, through the intervention of God. Examples are given in the Bible, such as Moses drawing forth water from the rock, or Aaron's staff being turned into a snake. However, in general, the Jews frowned upon the use of Practical Kabbalah. They had some justification for this: since, from a certain point of view at least, it could be seen as "interfering" with the proper and intended operation of God's Universe.

Lurianic Kabbalah: after the expulsion from Spain, a new centre of Kabbalistic learning was set up in Safed, in the Holy Land. By the middle of the 16th Century, it came under the leadership of Isaac Luria, also known as the Ari (the Lion). Luria revolutionized and recodified the Kabbalah - though he was a reluctant man of letters and it was left to his students to record most of his teachings. His new system was fantastically complex and in some instances raised more questions than it answered. Nevertheless, it did shed light on some of the more obscure corners of earlier writings, such as the Zohar. Luria advocated Mystical Kabbalah, but most of what was recorded was of a Contemplative nature. He shunned, and advised against, Practical Kabbalah, on the grounds that it was dangerous to interfere with the Universe in this way. These attitudes, coupled with the fact that after a lapse of many centuries, there was again a purely Jewish school of Kabbalah, operating in the Holy Land, away from non-Jewish influences, gave a renewed respectability to Kabbalah among the more Orthodox Jews. Central to Luria's ideas was the concept that the Universe we inhabit was the product of a kind of divine accident (Shevirat ha-Kelim, the "Shattering of the Vessels"), and that humanity's task is to assist in the Tikkun Olam, the "Restoration of the World". This concept has a special appeal today, when we are seeking to repair the physical nature of a world that has been damaged by our own carelessness in our treatment of the planet.

Christian Kabbalah: by the 17th Century, printed versions of the Zohar were available and in the middle of that century a Latin translation appeared of just a few dozen of the several hundred folios that it contained. The author of this work, Knorr von Rosenroth, had been struck by the content of the Zohar and by how readily its tenets could be applied to some of the beliefs that were considered central to the Christian religion. Sadly, Rosenroth's motives were far from pure: he imagined that, by using Kabbalistic arguments, he could persuade the Jews to convert to Christianity. With hubris like this, it is fortunate that the notion of a specifically Christian Kabbalah died out very quickly. Nevertheless, Rosenroth had (perhaps unintentionally) rendered a valuable and important service to the world; he had shown Christians that there was much in the Kabbalah that could help them to understand their own faith; and he had exposed the Kabbalistic texts to a wider audience in a freethinking age which included the traditions of Alchemy, Rosicrucianism, Freemasonry and Templarism, all of which were profoundly influenced by the Kabbalah.