Two nights ago I led a Tikkun Shavu’ot at a synagogue in Los Angeles. It bore the grand title of “Drawing Infinite Meanings from Divine Revelation of Torah.”

A “Tikkun Shavu’ot,” for the uninitiated, is an old Jewish custom of staying up till dawn in religious study on the first night of the holiday of Shavu’ot or Pentecost, the traditional date of the giving of the Torah at Mount Sinai. In Los Angeles, a city that does not put great stock in tradition, we knocked off before midnight. Still, that meant a couple of hours of close group reading of a text – in this case, one from the early rabbinic compendium of Exodus Rabba, redacted in Palestine in the first centuries of the Common Era, from which I chose a chapter dealing with the Bible’s account of the Revelation at Sinai.

To get back to infinity, though: It’s not a concept that was well-developed in antiquity. Ancient philosophers and religious thinkers alike in ancient times thought of the universe as finite, and even if the God who created it was not, they did not much dwell on what this meant. Trying to puzzle infinity out philosophically is something that began only in the early Middle Ages.

And yet the ancient rabbis had a problem nonetheless. When God sought to reveal Himself to mankind via His covenant with the Jewish people, He did so by means of a book – the Bible – that had in it a set number of chapters and verses. How could the wisdom of a God who, as Isaiah put it, “hath measured the waters in the hollow of his hand, and meted out heaven with the span, and comprehended the dust of the earth in a measure, and weighed the mountains in a scale” be contained in a single book? How could an infinite mind be revealed in a finite text?

The rabbinic solution to this conundrum was both simple and startlingly revolutionary. It was called Midrash, from the Hebrew verb darash, “to pursue the meaning of,” and it was built on two assumptions. The first of these was that every single word, verse, and even letter in the Bible is there for a reason, since God would never repeat Himself or say anything unnecessarily. The second is that every word, verse, and letter is related to every other word, verse, and letter, so that the sum total of the Bible’s meanings is the product of everything in it multiplied by everything else – which for all practical purposes is infinite.

Let’s take a simple example of how this works. In the account of Revelation in the 20th chapter of the book of Exodus, we are told that “Moses went up [on Mount Sinai] unto God,” while in the 68th chapter of the book of Psalms, we have the verse, “Thou hast ascended on high, thou hast taken captives.” Since this chapter of Psalms never mentions Moses, our second verse would seem to have nothing to do with our first one – but in a book of infinite meaning, as we have said, there is no such thing as “having nothing to do with.” Exodus Rabba therefore connects these two verses by parsing Psalms as meaning that Moses, like Prometheus stealing fire from the gods, had to ascend to heaven in order to “capture” the Torah from the angels, who were jealous of the human race for receiving it.

Utterly fanciful? Indeed it is, and there is in fact a good deal of fancy and playfulness in Midrash. And yet the enterprise behind it is deadly serious: It is the determination to ferret out, even if it takes forever, every last iota of significance in God’s word to man. Ultimately, in its higher sense, this is what the entire vast corpus of rabbinic literature is about.

Although Midrash may seem and is an esoteric activity, it was the beginning in human history of a perspective that only in our own postmodern times has become a widely accepted one – i.e., the belief that all things are interconnected; that there is no fixed or final set of meanings attached to any of them because there is always more to be learned and discovered; and that, therefore, the truth is necessarily relative, since reality can be interpreted in endless ways. All of contemporary, 21st-century science and philosophy rests in one way or another on these assumptions.

One generally thinks of a literal belief in divine revelation as going together with a constricted point of view that accepts only one vision of things – and, indeed, this is what fundamentalist religion, whether Jewish, Christian, or Muslim, does. And yet Exodus Rabba tells us the exact opposite. Why, it asks, does it say in Psalms, “The voice of the Lord speaks in power” rather than “in His power”? Because, it answers, the word “power” in this verse refers not to God but to human beings, each of whom understands the Torah according to his or her individual “power” or ability. God spoke at Sinai in different voices to each one of us.

This is an insight that even traditional Judaism found too radical for its liking and sought to bury beneath a more authoritative approach to religious truth. And yet it is, in its origins, a Jewish one. Every human mind has a contribution to make because only all minds working together can reconstitute the infinite complexity of the divine mind. That’s indeed something to stay up all night thinking about.

Mr. Halkin is a contributing editor of The New York Sun.