Symbolism, which initially emerged in Paris as an avant-garde literary movement, became prominent in major cultural centres across Europe in the late 1880s and 1890s. In their art and writing the Symbolists articulated their affinity to Idealist concerns and aspirations to express the eternal, immutable and intangible. Influenced by Baudelaire's theory of correspondences, that implies that the material world is linked to the spiritual and that the curious and sensitive artist could perceive a glimmer of the Ideal through fleeting sensations, the Symbolists developed new visual and poetic languages and adopted strategies such as the fragmentation of text, idiosyncratic use of symbolic, hyper-sensual and synaesthetic imagery, ambiguity and obscurity. While the Symbolist's nihilistic tendencies were recognised by peers and critics in relation to the poets, they have not been adequately acknowledged in regard to the visual artists. In this thesis, focusing on the art critic and novelist Joris-Karl Huysmans (1848-1907), I consider the Symbolists' claims of Idealism. I argue that Huysmans' powerful critical insights, while aligned with the Symbolist movement, stemmed not from Idealist convictions but from metaphysical questioning and anxiety as he wavered on the brink of an intellectual and spiritual abyss. Having outlined the evolution of Huysmans' aesthetic and metaphysical position, I consider how the complexity of his ideas ‚Äö- often articulated through references to disease and mortality, and juxtaposition of these against Symbolist tropes alluding to the immutable and eternal ‚Äö- informed his critical approach and elucidate nihilistic tendencies in the work of artist Mathias Gr‚àö¬¿newald (1475-1528), and Symbolist artists Gustave Moreau (1836-1898), Odilon Redon (1840-1916) and Felicien Rops (1833-1898).