This chapter develops and analyzes how thought experiments connect thinking with actuality. Superficially, imaginary constructions are mere possibilities that diverge from actuality. However, Kierkegaard also characterizes thought experiments as a kind of experience, providing concrete, fulfilling content for an otherwise empty concept – that is, providing what Kant calls a “synthesis” between thought and experience. Two Ages shows how the work of synthesis can begin from observations and move toward understanding or from understanding toward fulfillment in experience. In Works of Love, I propose, we find material for a basic taxonomy of thought experiments that distinguishes them by whether the thought experiment offers cognition of (a) objects or (b) concepts and whether it (a) proceeds from existing concepts or (b) guides the reader in gaining new ones. This taxonomy mirrors Kant’s distinctions between constitutive and regulative concepts and determining and reflecting judgments. It also anticipates the proposals of recent rationalist accounts of intuition that thought experiments provide nonsensory presentations.