This dissertation develops a philosophical reading of illness, equally as motive and concept, in four modernist novels – The Magic Mountain by Thomas Mann, The Dried-up Mire by Janko Polić Kamov, Zeno's Conscience by Italo Svevo, and Moravagine by Blaise Cendrars. The work consists of two central lines or thematic complexes which correspond to two meanings that illness acquires in those novels, and these are: a) neurosis, together with its place in the modern culture and the role in the formation of a modern subject, and b) the metaphysics of illness as a specific attempt at articulating materialist philosophy and materialist understanding of the world, life, and reality in the aforementioned novels. The central part of the dissertation consists of the separate readings of each novel, which include the discussions of some other important aspects of those novels and the modern culture in general, such as nihilism, pessimism, eroticism, and misogyny. The conclusion is divided into two parts. The first part of the conclusion (or the first conclusion) summarizes the most important observations regarding the place and function of neurosis in four novels, while the second part (or the second conclusion) considers the connections between philosophical thinking found in the novels and philosophies of Georges Bataille and Gilles Deleuze, as well as philosophical projects developed under their influence (new materialism, libidinal materialism). The appendix, which is joined to the dissertation but which can also be read independently of it, briefly presents three theories of writing developed in the second half of the 20th century; all of which are occupied with the relation between writing and neurosis. The aim of the dissertation is twofold: a) to investigate the importance of neurosis for understanding the modernist novel and modern culture, and b) to point toward metaphysical ambitions of the modernist novel.