This paper attempts to clarify the process from the "elementary system of moving forces of matter" to "ether-deduction" focusing on the "perpetuity of motion" in Kant's last manuscript, "opus postumum". Kant described the perpetuity or continuation of motion under the category of the modality of a moving force. This means that quantity of motion (mv) is constant in the "whole-world". This whole-world is postulated as an idea, not as an absolute space in a Newtonian sense. The whole-world is not only the space in which mechanical laws are valid, but also the dynamical totality. Thus, the beginning of the world is explained dynamically. As the originator of movement or "first mover", Kant assumed the existence of ether or caloric, whose existence was proposed in a manuscript written around 1799. These discussions involve the scope of the theory of time. The concept of perpetual motion refers to a uniform linear conception of time, which can be described by uniformly flowing time. In conclusion, I suggest that, in Kant's conception, the beginning of the world is dynamical while its continuation is mechanical.