The opening of the book includes a preface, wherein Blavatsky expresses her intention to apologize for the lengthy delay in its publication due to health issues and the complexity of the subject matter. She acknowledges that the text is not a revelation but seeks to aggregate long-hidden truths found in various ancient belief systems. The first chapter introduces the concept of a pre-historic manuscript, setting the stage for discussions on cosmic evolution, symbolisms, and the philosophical implications of unity within diversity. Blavatsky's tone is both apologetic and assertive as she positions her work as an essential contribution to the understanding of ancient mystical teachings, setting the groundwork for the intricate discussions that follow in the subsequent sections. (This is an automatically generated summary.)