The objective of this article is to show how experimental discoveries in atomic physics are logically connected, and we land up with the consistent theoretical explanation to the structure and stability of the atom. It is also shown that Bohr’s correspondence principle and Erhenfest’s adiabatic invariant hypothesis act as a guiding rules to this route. As a generalization to Bohr’s quantum condition, the Wilson-Sommerfeld quantization condition for multi-periodic system is presented with a derivation.