Although Stevens held that "All of our ideas come from the natural world: Trees = Umbrellas", his imagination revealed nature as enigmatic. Bates notes that many of Stevens' images and symbols "combine clarity with an air of mystery". "The Public Square" illustrates this quality. Buttel explains this mysterious naturalism as Stevens' response to the ethos of the Symbolists which brought him to take his earlier transcendentalist leanings, towards a union of nature and the ideal, "in the direction of the dark and mysterious". He was led to become urgently concerned with conveying the indefinable in the poem itself. "The Curtains in the House of the Metaphysician" is as good an example as any. He redirects the longing to know a transcendent realm into nature itself, salving the frustrated platonic desire with his poetic gifts, notably the non-discursive effects borrowed from sound and sight, music and painting. He is ironic, as in "Invective Against Swans" and "Anatomy of Monotony", about the 'spiritual' demand to transcend nature. Another aspect of Stevens' naturalism is his close attention to the perceptual act, particularly as not simply mirroring reality but rather as disclosing it in this or that creative aspect. This is arguably the subject of "Tattoo".