The fundamental goal of this chapter is to answer the question, in which sense is the horizon a specifically philosophical notion and a specifically philosophical theme. With this in mind, the chapter examines how Husserl's notion of the horizon derives from James' analysis of the halo, background, and fringe of consciousness. I argue that Husserl is to be considered the founder of the horizon-problematic in philosophy, yet not because he was the first to have thematized the phenomenon of the horizon. James had already done so at a great depth. The significance of Husserl's analyses consists in having depsychologized the horizon-problematic and in having disclosed its transcendental dimensions. Thus, as a philosophical notion and a philosophical theme, the horizon is irreducibly transcendental. The single most significant philosophical upshot of such a transformation consists in eliminating arbitrariness that is entrenched in James' notion of the fringe of consciousness. Far from compromising the phenomenon's objective sense, the subject-relativity of the horizon is what allows one to identify and secure the phenomenon's objective significance.