The narrative theme of the Third Day is the coupling of "desire" and "industria" or ingenuity ("the discussion turns upon people who by dint of their own efforts have achieved an object they greatly desired, or recovered a thing previously lost"). The symbolic framework that links together all the various stories is the imagery or the "topos" of the "garden of delights," whose description we find in the Author's introduction to the day (the author as the narrator of the frame story).
The garden is the symbolic place where Nature and human Ingenuity (instinct, desire and industria) join together: it is a place of beauty, of natural luxury, but also of order, symmetry and artful rules: "the overriding strain of (its) description is the bounty of a generous nature -- the place swarms with the infinite variety of living things. But the natural cycle of the seasons... is suspended" (Mazzotta). The ten narrators are suspended in an eternal spring; this is the ideal setting for storytelling as a pleasurable activity, among other forms of social entertainment (games, songs, dance etc.) in short, it is the symbolic setting of the Decameron's utopia.
Within the garden, there is another, more secluded garden: an enclosed garden, a walled-in space whose most significant model is the garden of Love in the Roman de la Rose (by Guillaume de Lorris). According to Mazzotta, Boccaccio's introduction to the third day is, like Guillaume's poem, "a subtle mockery of the religious quest for Eden, and even more precisely a parody or a "spoof" of "Dante's allegory of the spiritual pilgrimage." In Dante's Comedy, the poet and his guide and mentor, Virgil, climb from the abyss of Inferno to the top of the mountain of Purgatory, located in the Southern hemisphere (down under). On this mountain top is the garden of Eden (see Dante's description, Purg., canto XXVIII-ff.). Here Dante meets again his beloved and long dead Beatrice who will guide him from the earthly to the heavenly Paradise.
In the Decameron, the garden has a meta-narrative, i.e. self-referential function. The garden symbolism is not only a reference to the day's narrative theme, the conquest of the garden of delights, i.e. the fulfillment of sexual or amorous desire through ingenuity, eloquence and wit, but can be also linked to storytelling: as a game played in the garden, storytelling is the esthetic "sublimation" of lovemaking, for whose delights its pleasure is a sort of substitution. In other words, the garden is the laboratory of storytelling, the magic space where the narrators can experiment, almost in suspended animation, with all the expressions of and moral issues raised by lovemaking in society. This will become very clear in the introduction to the following day, the Fourth, where, in the most important intervention of the author in his own text, Boccaccio's ideas about love and erotic desire are exposed as inextricably intertwined with his ideas about storytelling, in a compelling self-defense of his own rights as an artist.