In Husserl’s Ideas of 1913, we find that the concept of world is ambiguous, for it is firstly interpreted as a horizon experienced in perception, and secondly as a totality of objects known in terms of theoretical thought on the basis of direct experience. In the Cartesian Meditations of 1929, Husserl still retains these concepts, but suggests a new idea, genetic phenomenology, which advocates that a philosophical understanding of an object must trace the constitutive history of its meanings which have been deposited in the process of its constitution. This tracing of the history of its constitution requires that the higher constituted products refer to the lower constitutive primordial experience as the foundation of that history. In the Crisis, Husserl criticizes his previous “Cartesian way” to phenomenology in which the transcendental epoche is a “nullification of a thing-world”, and thus, that will be empty of content for philosophical study after epoche. Husserl suggests an “ontological way” in which the transcendental epoche is a total change of attitude, i.e., it does not “nullify the thing-world”, but brackets the higher deposited meanings in order to search for the lower constitutive primordial experience that is the foundation of constitution. Husserl finds that the primordial experience is perception, and the world correlated to perception he calls the life-world. Thus the perceptual world has become the foundation of the world known in theoretical thinking. The two ideas, genetic phenomenology and transcendental epoche as a total change of attitude, are the reasons that the later Husserl came to consider the perceptual world as foundation.