It's not just that they're natural antagonists, but that they seem to inhabit two different, never-intersecting planes. Faith is unequivocal; reason is reasonable. Faith is supra-human and thus (to us) unreal; reason is realness made human-sized, defined and confined, drained of wonder and life. For many centuries each dwelled on its plane with its loyalists, viewing the other with suspicion, even disdain.
Until there came a man who was a citizen of both worlds. He passed freely from one to the other, building bridges between them, describing a symbiotic faith-reason universe in which each flows into, feeds on, and buttresses the other.
His name was Rabbi Schneur Zalman of Liadi, born in Li'ozna, White Russia in 1745. As a young man he joined the Chassidic movement, founded a generation earlier by Rabbi Israel Baal Shem Tov. By 1772, he was developing his own branch of Chassidism, which came to be known as "Chabad". In 1796 he published Tanya, the book which contains the fundamentals of his teachings, over which he labored for 20 years -- a book which prompted one of his great contemporaries to exclaim, "How did he put such a great G-d into such a small book!" By the time of his passing in the winter of 1812-3, he had sown the kernels of the seven generations of Chabad teaching and activism that were to revolutionize Jewish life across the globe.
The intellect and the powers of the mind play a central role in Rabbi Schneur Zalman's system. Study, comprehension and meditation are the tools by which faith is internalized and made real, so that permeates the person, developing and guiding his emotions and motivating his actions. Indeed, the name "Chabad" is an acronym for the Hebrew words for "wisdom", "understanding" and "knowledge", and Chabad is often referred to as the "intellectual branch of Chassidism."
That categorization is not entirely correct. Rabbi Sachneur Zalman was not an "intellectual" -- at least not in the common sense of one who regards the intellect as the ultimate arbiter of truth. On the contrary: he taught that ultimate truth lies in our deeply-held convictions, in the things we know without understanding them -- in the beliefs that are ingrained in our self-awareness by virtue of our soul being a spark of the Divine. In fact, the intellect will often suppress and distort these truths. But that is only when the intellect's function is misapplied -- when it sees its own bounds as absolute, and what lies beyond them as beyond its ken. True intellect, said Rabbi Schneur Zalman, is receptive to the supra-rational, and harnesses its own tools to the task of apprehending it and "internalizing" it.
The fact that you cannot rationally understand something is no reason not to study it. You know it to be true -- your deepest self tells you it is. So contemplate it, analyze it, meditate upon it. Don't be intimidated by your mind's initial inadequacy. When you embrace faith's infinitude with your mind's finite tools, you'll eventually find those tools "expanding" to receive it. And you'll find your finite reality saturated with the divine supra-reality you've always regarded as "beyond" you.
A group of Rabbi Schneur Zalman's disciples were once discussing the Messianic Age and the great miracle of "the revival of the dead" destined to then take place, when one of them said: "But we see this miracle every day! Our own master has this power -- he, too, revives the dead. What is a corpse? Something cold and unfeeling. Life is movement, warmth, excitement. Is their anything as frozen in self-absorption, as cold and unfeeling as the mind? And when the cold-blooded mind understands, comprehends, and is excited by a G-dly idea -- is this not a revival of the dead?"
