In previous work, we proposed a unified generative principle for physical scales based on the discrete double-exponential function Nx = exp(exp(x)), where x ∈ Z is an integer scaling parameter. This hypothesis precisely predicts 15 fundamental physical constants spanning from microscopic to cosmic scales. However, the theory lacked a derivation from first principles. In this work, we propose that this macroscopic hierarchy emerges directly from the microscopic dynamics of E8 Toda Field Theory. We demonstrate that the exponential interaction potential V (ϕ) ∼ e ϕ dictated by the E8 root system, combined with the Hagedorn density of states in string theory, naturally leads to a double-exponential partition function. Furthermore, we introduce a Topological Locking mechanism based on Chern-Simons flux quantization, which constrains the continuous field ϕ to discrete lattice points, thereby explaining the integer nature of the hierarchy parameter x. This framework provides a complete theoretical closure from geometric structure to observed physical constants.