At the far end of the world there is a mountain, on the mountain top is a rock, and a fountain of water gushes from the rock.
This you know: that everything in the world possesses a heart, and the world itself has a great heart. The heart of the world is complete, for it has a face, and hands, and breasts, and toes, and the littlest toe of the world's heart is more worthy than any human heart. So at one end of the earth there is the fountain that flows from the rock on the mountain top, and at the other end is the earth's heart.
And the heart desires the mountain spring; it remains in its place far at the other end of the earth, but it is filled with an unutterable longing, it burns with an endless desire for the distant fountain of water...
Because of its great longing, it sometimes tries to go to the fountain, but if it goes nearer to the foot of the mountain it can no longer see the spring on the top of the mountain, and so it must remain far away, for only from a distance may a mountain peak be seen. And if it were for an instant to lose sight of the spring, the heart would die, and then all the world would die, for the life of the world and everything in it is in the life of its heart.
So the heart remains longing at the other end of the earth, longing for the spring that cannot come toward it, for the spring has no share in Time, but lives on a mountain peak far above the time that is on earth. And the mountain spring could not be of the earth at all, since it has no share in the earth's time but for the earth's heart, which gives the spring its day.
And as the day draws to its close, and time is ended, the heart becomes dark with grief, for when the day is done the mountain spring will be gone from the earth, and then the earth's heart will die of longing, and when the heart is dead all the earth and all the creatures upon the earth will die.
And so, as the day draws to a close, the heart begins to sing farewell to the fountain; it sings its grief in wildly beautiful melody, and the mountain spring sings farewell to the heart, and their songs are filled with love and eternal longing.
But the Truly Godly Man keeps watch over them, and in that last moment before the day is done, and the spring is gone, and the heart is dead, and the world is ended, the good man comes and gives a new day to the heart; then the heart gives the day to the spring, and so they live again.
The symbolism seems clear to me. The "heart of the world", and the spring issuing from the mountain, represent the human soul and God. It is not obvious which is which, but my inclination is to identify God with the spring. This is because water symbolizes Torah; Mt. Sinai had a spring issuing from it (Shemot 17:6, 32:20, Devarim 9:21); and the spring "could not be of the earth at all... but for the earth's heart" - that is to say, God is transcendent and absent from the world, except in the human soul, while the human is fundamentally part of the "earth" or physical world.
The soul and God sense each other and try to meet one another. But exactly at the moment of closest approach, the line of sight between "heart" and "spring" (man and God) is blocked. The "heart" and spring sing love songs, but can no longer approach one another. Eventually the day ends: the failure of man and God to meet results in frustration and eventual abandonment of the task. But when all seems lost, another day begins, and God and man's struggles to meet each other begin again from scratch.
The dynamic here is very similar to what R' Soloveitchik describes in his book "Uvikashtem Misham". There, drawing on the metaphor of Shir Hashirim, God is the male lover and humanity the female. God knocks on our door, but we are lying in bed and at first do not have the energy to get up and answer. When we finally get to the door, God has already stopped waiting. We then go out and search the streets for God, who is presumably only a short way off, but without success. Then, it is implied, we return home and the story repeats itself. Both sides passionately desire a meeting, but at no point does the meeting ever occur.
Both of these stories seem overly pessimistic, as the cycle repeats itself without God and humanity ever managing to meet. I can think of two responses to this criticism. First, at least in R' Soloveitchik's metaphor, it is possible that despite all the failures so far, the two sides will someday succeed in meeting. Second, eventual failure is not necessarily a pessimistic conclusion. All human lives are destined to fail, through death. But that eventual failure does not erase the value of efforts performed beforehand. Similarly in our stories, the effort is valuable and "on the record", even if the desired conclusion is not obtained.
When reading a religious parable as complex and poignant as these two are, it's hard to escape the conclusion that the author is describing their personal experience in all its depth and detail. Perhaps no two Jewish leaders have inspired more dissimilar followers than did R' Nachman and R' Soloveitchik. For that reason, it's interesting how the two rabbis' religious experiences were so very similar.
Of course, the explanation may be that the kind of experience R' Nachman identified and tried to steer his followers away from, R' Soloveitchik identified and saw as ideal.