People are never very good at remaining silent. That’s true even for things we can’t talk about in ways that make any sense.
Kabbalah (Jewish mysticism)  is an extended exercise in talking about things we can’t talk about. As a result, it's easy to dismiss Kabbalah as mythology, poetry, and the fevered visions of madmen.
But that’s a mistake. Speaking in imagery and metaphor, Kabbalah points to some important truths about our world. It only points to them because it can’t articulate them, at least not very well. Neither can I. But they’re still true.
Jewish rationalists like me tend to regard Kabbalah as an embarrassment. But let’s take a cue from Yoram Hazony, who asked an interesting question about the Bible:
”What if the texts … or many of them are in fact much closer to being works of reason than anything else -- only we don’t know it because this fact has been suppressed (and continues to be suppressed) by an alien interpretive framework that prevents us from seeing much of what is in these texts?” 
Might the Kabbalah contain rational insights that we've overlooked because they’re stated in obscure and mythological terms? Philosophy has been defined as an attempt to answer three questions:
* What exists?
* How do we know?
* Therefore, how should we live?
A key insight of Kabbalah, and of mysticism generally, is that some answers to the first question -- What exists? -- elude our ability to understand or express in language. Because the answers can’t be expressed in language, Kabbalists can't simply state them. Instead, they try to lead us to the answers by devices such as images, meditations, rituals, and stories. Some of the answers seem to be:
* God causes everything to exist. 
* God is both transcendent and immanent. In one sense, God is separate from the world, and in another sense, God is in everything.
* God uses language to create the world we see around us.
* The world has an underlying unity. Our separation of reality into different things, times, places, and events is a superficial illusion.
A contemporary example of this view is given by Arthur Green, one of our professors at Hebrew College:
”Unity is the only truth, and all divisions of reality, including the most primal dualities (God/world, good/evil, male/female, and lots more) are relative falsehoods. That does not mean, I hasten to add, that we can or should live without them.” 
One Kabbalistic source of answers to the first question is the Sefer Yetzirah (The Book of Creation). We aren’t sure exactly when it was written or by whom, though it was probably written between the first and ninth centuries CE. It describes the world as having three layers: cosmos, time, and humanity. God created the world by using the 22 letters of the Hebrew alphabet and 10 sefirot:
”With 32 mystical paths of Wisdom engraved [Hashem], the Lord of Hosts, the God of Israel … And He created His universe with three books: with text, with number, and with communication.” 
Rabbi Aryeh Kaplan (1934-1983) explains:
”These 32 paths are manifest as the 10 digits and the 22 letters of the Hebrew alphabet. The 10 digits also manifest in the Ten Sefirot, which are the most basic concepts of existence … The letters and digits are the basis of the most basic ingredients of creation, quality and quantity … Numbers, however, cannot be defined until there existed some element of plurality [which] came into existence only with the advent of creation.” 
Another writer explains the implications:
”The idea that the universe was created by Divine speech is an ancient one in Judaism, and the Sefer Yetzirah developed it systematically. The principle seems to be that if creation is accomplished by language, then the laws of creation are the laws of language. Grammar was thus conceived as the basic law of nature … Everything in the universe, following grammatical principles, has two aspects, parallel to the gender duality of masculine and feminine.” 
That sounds familiar in a couple of ways.
First, it’s consistent with Ancient Near Eastern ideas about what it means for something to exist:
“In the ancient world something came into existence when it was separated out as a distinct entity, given a function, and given a name.” 
Second, it sounds a lot like the ideas of rationalist philosophers in our own era. They argue that mind creates the world by superimposing a layer of plurality over an underlying unity. On their view, whatever the ultimate nature of reality is, reality for us inevitably refers to the minds that experience and understand it:
”In one sense my mind is in my head, in another sense my head is in my mind. In one sense I am in space, in another sense space is in me.” 
University of Pittsburgh philosopher Nicholas Rescher explains further:
”The very being of a particular [thing] lies in its possession of a distinguishing individuality. But the very idea of an individual calls for the existence of criteria of identity to specify how it would be distinguished from other individuals. And a criterion is an inherently mind-invoking conceptual resource.” 
In other words, the existence of separate things, in various categories and with various names, depends on a mind that separates them, puts them in categories, and gives them names -- Just as the Sefer Yetzirah attributes to God’s creative activity. Without such conscious activity, the world remains “formless and void.”
Metaphysics and Mythology
What might have happened is that the Kabbalistic writers were trying to understand two kinds of realities: transcendent realities involving God, and non-transcendent realities involving the world and how it came into existence.
As they contemplated transcendent realities, the Kabbalists dreamed up all kinds of images and metaphors in their attempt to comprehend the incomprehensible. When they turned their attention to more mundane realities that were actually comprehensible, they still thought in terms of the fantastic imagery they'd constructed to picture the Divine -- so that's what they used. The result was to obscure instead of instruct.
There's a lot in the Kabbalistic literature, both for philosophical insights and for purely artistic enjoyment. We shouldn't dismiss Kabbalah simply because it's become a popular tourist destination for Gentile celebrities.
Bosanquet, B. (1895), Essentials of Logic. Kraus Reprint Company, New York.
Dan, J. (2006), Kabbalah: A Very Short Introduction. Oxford University Press, Oxford, UK. Kindle edition.
Green, A. (2003), Ehyeh: A Kabbalah for Tomorrow. Jewish Lights Publishing, Woodstock, VT. Kindle edition.
Hazony, Y. (2012), The Philosophy of Hebrew Scripture. Cambridge University Press, Cambridge, UK.
Kaplan, A., translator (1990), Sefer Yetzirah: The Book of Creation. Samuel Weiser, Inc., York Beach, ME.
Matt, D. (1995), The Essential Kabbalah. HarperCollins, New York.
Rescher, N. (1973), Conceptual Idealism. Basil Blackwell, Oxford, UK.
Walton, J. (2006), Ancient Near Eastern Thought and the Old Testament. Baker Academic, Grand Rapids, MI. Kindle edition.
Wittgenstein, L. (1961), Tractatus Logico-Philosophicus. Routledge & Kegan Paul, London, UK.
1. Wittgenstein, L. (1961), p. 150. My translation of the German text “Wovon man nicht sprechen kann, daruber muss man schweigen.”
2. The term “kabbalah” has been used to refer to Jewish mysticism, non-Jewish mysticism, and to non-mystical elements of the Jewish tradition. This blog post is only about the first.
3. Hazony, Y. (2012), p. 1.
4. Causation by God is not causation in the normal, scientific sense. It does not occur in time, although we might perceive it that way. Divine causation is beyond our understanding.
5. Green, A. (2003), loc. 132.
6. Kaplan, A. (1990), p. 5.
7. Ibid, p. 5.
8. Dan, J. (2006), loc. 412.
9. Walton, J. (2006), loc. 1466.
10. Bosanquet, B. (1895), p. 17.
11. Rescher, N. (1973), p. 99.