The quatrain is the last stanza of the poem Gesang der Geister über den Wassern, which Goethe wrote in 1779 during a stay in Switzerland. The poem was inspired by the Staubbach Falls near the village of Lauterbrunnen.
In order to understand the comparisons in the last stanza, it is helpful to discuss what the poem is about. The first stanza compares the human soul with water; the soul has a heavenly or godly origin, so that where it eventually strives to return.
The second stanza describes water coming down from an overhanging cliff and turning into a spray, much like the Staubbach Falls. Instead of a thunderous cascade, the result is more like a mist that gently lands at the bottom, representing a life without much struggle or suffering.
The third stanza contrasts with the preceding one: rocks at the bottom cause the water to foam, representing a life with more challenges and struggles.
In the fourth stanza the water ends in a placid lake which probably represents tranquillity in later life. However, the fifth stanza describes how the wind can be a soft breeze that merely ripples the water (creating a parallel with the easy life in the second stanza) or a force that moves even the deeper waters and causes foaming waves (creating a parallel with the fourth stanza).
The sixth stanza uses the word "Seele" again. However, while translating this noun as "soul" makes sense in the first stanza, it is important to bear in mind that Seele can also mean "mind" or "spirit", which is more closely associated with emotions. For example, when Faust says (in Faust I), "Zwey Seelen wohnen, ach! in meiner Brust", this is usually translated as "Two souls [reside in my breast]". However, he is not referring to souls in a Christian sense but expressing an inner conflict. Similarly, the human mind can be placid or stormy (like water) depending on how strongly fate (the wind) moves it.
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