The tractate of Chagigah teaches … [about the] seven heavens, one above the other.
Above the heavens are the holy angels, the chayyot, and “the feet of the chayyot measure up to all.”
The feet of the angels, their lowest part, exceed in size all the worlds and heavens beneath them.
The principle at work here is that the lower level of a higher world is always loftier than the upper level of the world beneath it.
The sign of real development, then, is that one’s previous level no longer holds true for him.
When one genuinely grows, his personal truth now must surpass all his previous truths so that, by comparison, they are not true at all.
The author of the Tanya demands from the beinoni [intermediate one] that he pursue his individual truth at all times.
Yesterday’s heavens should be today’s earth, and he must know: there is a truth still higher than this.
—Rabbi Adin Steinsaltz