To me Temperence is a card of Unification, of the defining space between differences.
The angel stands with a foot in each of the worlds of mind and matter, pouring "the essence of life" [Waite] between the inner and outer worlds. The flower is the iris, the rainbow goddess, bridge between worlds, messenger and psychopomp. As such it is a card of linkage and passage between opposites, extremes, and worlds (it is the card which immediately follows Death).
The crown at the end of the path is the natural conclusion of what we have here; the ultimate unity between the individual and the All. The path takes us from here to There, but only when we can bring the extremes in our natures into balance can we undertake the path to the Ultimate Being - the One who dwells in Kether (which means "crown") and is simultaneously far from us at the top of the Tree of Life and 'immanent', right here right now, enclosing us all.