After completing Letter III: From Information Geometry to Information Gravity, I recognized the importance of offering a deeper reflection on the motivations that led me to develop the Theory of Entropicity (ToE). To provide readers with a clearer understanding of the origins, evolution, and conceptual trajectory of the theory, I have written this Letter III‑A as an extended exposition on the intellectual path that brought ToE into being. When I concluded Letter III, which traced the path from information geometry to information gravity, it became clear to me that the story behind the Theory of Entropicity deserved its own dedicated treatment. The motivations, insights, and conceptual breakthroughs that shaped ToE are as important as the Theory’s concepts and mathematics, and its subsequent derivation of Einstein’s Gravity. Letter III‑A therefore serves as a reflective companion piece, illuminating the origins and development of the Theory of Entropicity (ToE): Entropy is primary.