Water is the commonest symbol for the unconscious.
The lake in the valley is the unconscious, which lies, as it were, underneath consciousness, so that it is often referred to as the “subconscious,” usually with the pejorative connotation of an inferior consciousness.
Water is the “valley spirit,” the water dragon of Tao whose nature resembles water—a yang embraced in the yin.
Psychologically, therefore, water means spirit that has become unconscious.
So the dream of the theologian is quite right in telling him that down by the water he could experience the working of the living spirit like a miracle of healing in the pool of Bethesda.
The descent into the depths always seems to precede the ascent.
Thus another theologian 20 dreamed that he saw on a mountain a kind of Castle of the Grail.
He went along a road that seemed to lead straight to the foot of the mountain and up it.
But as he drew nearer he discovered to his great disappointment that a chasm separated him from the mountain, a deep, darksome gorge with underworldly water rushing along the bottom.
A steep path led downwards and toilsomely climbed up again on the other side.
But the prospect looked uninviting, and the dreamer awoke.
Here again the dreamer, thirsting for the shining heights, had first to descend into the dark depths, and this proves to be the indispensable condition for climbing any higher.
The prudent man avoids the danger lurking in these depths, but he also throws away the good which a bold but imprudent venture might bring. ~Carl Jung, CW 9i, Para 40-41