Moses, whose name means drawn out of water, is the higher self in its infancy, the spark of awakening that cannot stay hidden in the flesh forever. The ark of bulrushes is the body itself, the fragile vessel of reeds sealed with slime and pitch, made just watertight enough to carry the divine seed through the currents of ordinary life. The child set inside is the inner spirit riding within its earthen craft.
The river is the flow of the emotions and the stream of time, and the reedy brink where the ark is laid is the border between the subconscious depths and the waking world, the exact edge where the hidden self waits to be found and drawn up.
Moses: the higher self as newborn spark, the one drawn out of the waters of the flesh
Ark of bulrushes: the physical body, the frail sealed vessel of reeds bearing the divine seed through life
Slime and pitch: the coarse material of matter that makes the body hold together and float
River: the flowing emotions and the current of time in which the spirit is set adrift
Flags by the river's brink: the reedy border between the subconscious and the waking mind