This text analyzes the evolution of the concept of transcendental idealism, tracing its path from Kant’s formal a priori preconditions of cognition to Husserl’s phenomenology and Patočka’s negative Platonism. The author examines the transformation of formal conditions of experience into material ones by subjectivizing reality through the lens of phenomena. Husserl’s approach, which distinguishes between things-in-themselves and the way they appear, sets the stage for Patočka’s reform of Platonism. In this framework, ideas are interpreted not as true entities or beings, but as negative entities or non-beings. A crucial development is the shift in the temporality of these ideas: moving from timeless universal principles to forces arriving from a non-objective future toward the individual. Through this individual engagement and action, ideas become objectified and enter historical time. The text provides a concise insight into the ontological and temporal shifts within modern philosophy, leading from static structures to a dynamic understanding of meaning and history.