In this study, Sabahattin Ali’s novel Kuyucaklı Yusuf will be analysed by focusing on the concepts of conatus, potentia agendi and potestas in Baruch Spinoza’s philosophy. The novel is based on how Yusuf’s struggle for existence is suppressed within a strict hierarchical order. Spinoza defines conatus (striving for existence), one of the basic concepts of his understanding of existence, ethics and freedom, as the effort of every being to maintain its own existence. According to Spinoza, who explains human emotions (affectus) in the context of conatus, the human endeavour to sustain its own existence is directly related to the feelings of pleasure and pain. While pleasure (laetitia) is a positive affect that increases the capacity of human activity, pain or sadness (tristitia) indicates a decrease in the same capacity. These affections are directly related to conatus, the power of the being to sustain itself. Yusuf’s conatus, that is, his inner endeavour to sustain and strengthen his own existence, is shaped by his desire for love for Muazzez. However, this orientation is in constant conflict with the potestas (power) structure formed by the figures representing authority in the provincial order. Representatives of the spheres of power such as the judiciary, bureaucracy, security and local notables hinder Yusuf’s endeavour for existence. Especially the death of his beloved and his father produces a state of intense sadness that weakens Yusuf’s effectiveness. Thus, Yusuf’s conatus, initially fuelled by pleasure, evolves into an existential process that is gradually dissolved by potestas. In the study, Yusuf’s struggle to protect his freedom, his capacity to act in accordance with his own nature and his power of action (potentia agendi), which expresses his liberation with the increase of this capacity, are revealed. In addition, the tragic break he suffered in the face of potestas (authority), an external authority that represents the institutional and authoritarian powers of the social structure and restricts the power of individuals to act, is analysed.