The phase space of a light quantum in a given volume is divided into "cells" of size \( h^3 \). The number of possible distributions of light quanta within these cells, which determines the entropy and all thermodynamic properties of the radiation, is derived from Planck's formula for the energy distribution in the radiation of a black body. This formula serves as the starting point for the quantum theory that has been developed over the past 20 years and has had significant applications in various areas of physics. Planck's formula, first published in 1901, has been derived in many ways, but all previous derivations rely on the relation between the radiation density and the average energy of oscillators, which is rooted in classical electrodynamics. This relation, \( q_v \, d\nu = \frac{8\pi\nu^2 d\nu}{c^3} E \), introduces assumptions about the number of degrees of freedom of the ether, which can only be derived from classical theory. This logical flaw has led to efforts to derive the formula independently of classical theory. Einstein provided an elegant derivation that recognized this logical flaw and aimed to deduce the formula from simpler assumptions about energy exchange between molecules and the radiation field. However, to align with Planck's formula, Einstein had to use Wien's displacement law and Bohr's correspondence principle, which are based on classical theory and assume agreement with classical theory in certain limiting cases. The author argues that the combination of the light quantum hypothesis with statistical mechanics, as adapted by Planck for the needs of quantum theory, is sufficient to derive the law independently of classical theory. The method involves considering the radiation confined in a volume \( V \) with total energy \( E \), and determining the number of quanta \( N_s \) and their energies \( h \nu_s \). The probability of any distribution characterized by \( N_s \) is maximized under the condition that this probability is maximized while satisfying the given constraints. The quantum's momentum is characterized by its coordinates and momenta in a six-dimensional space, and the phase space is divided into cells of size \( h^3 \).The phase space of a light quantum in a given volume is divided into "cells" of size \( h^3 \). The number of possible distributions of light quanta within these cells, which determines the entropy and all thermodynamic properties of the radiation, is derived from Planck's formula for the energy distribution in the radiation of a black body. This formula serves as the starting point for the quantum theory that has been developed over the past 20 years and has had significant applications in various areas of physics. Planck's formula, first published in 1901, has been derived in many ways, but all previous derivations rely on the relation between the radiation density and the average energy of oscillators, which is rooted in classical electrodynamics. This relation, \( q_v \, d\nu = \frac{8\pi\nu^2 d\nu}{c^3} E \), introduces assumptions about the number of degrees of freedom of the ether, which can only be derived from classical theory. This logical flaw has led to efforts to derive the formula independently of classical theory. Einstein provided an elegant derivation that recognized this logical flaw and aimed to deduce the formula from simpler assumptions about energy exchange between molecules and the radiation field. However, to align with Planck's formula, Einstein had to use Wien's displacement law and Bohr's correspondence principle, which are based on classical theory and assume agreement with classical theory in certain limiting cases. The author argues that the combination of the light quantum hypothesis with statistical mechanics, as adapted by Planck for the needs of quantum theory, is sufficient to derive the law independently of classical theory. The method involves considering the radiation confined in a volume \( V \) with total energy \( E \), and determining the number of quanta \( N_s \) and their energies \( h \nu_s \). The probability of any distribution characterized by \( N_s \) is maximized under the condition that this probability is maximized while satisfying the given constraints. The quantum's momentum is characterized by its coordinates and momenta in a six-dimensional space, and the phase space is divided into cells of size \( h^3 \).