The word paradise is a garden word: Greek paradeisos, borrowed from the Old Persian for a walled enclosure, the pleasure gardens of Persian kings, chosen by the Greek translators of scripture for Eden and inherited by three faiths as the name of blessedness itself. The Quran's heaven is gardens beneath which rivers flow; the cloister garth kept a square of paradise inside every monastery; the Persian carpet spreads a garden underfoot in winter. When a dreamer walks in a dream garden, the oldest furnishings of the image are these.
Eden gave the garden its plot as well as its name: innocence held, lost and longed for, the gate and the flaming sword, the garden as the state that cannot be returned to but is never forgotten. The enclosed garden of the Song of Songs added intimacy, the hortus conclusus that medieval art painted around the Virgin, the garden as the guarded inner life itself.
The interpretive traditions read the dream garden on exactly that line: the inner life as cultivated ground, its flourishing and neglect as the dreamer's own tending, the wall as privacy or enclosure, the gate as what is admitted. Voltaire's counsel to cultivate one's garden serves the modern readings as motto without their needing to know the older lineage, but the lineage is why the image carries the weight it does; no other landscape has been the actual name of happiness in so many tongues.