In the earliest records we have of what the Buddha taught, the Path of Awakening is said to progress through four levels, culminating at the Fourth Level in the attainment of Nibbana (Nirvana). We call this the "Gradual Path" to distinguish it from the one-stage "sudden illumination" embraced by later forms of Buddhism. Despite the centrality of the Four Levels of Awakening to the Buddha's original teaching, we are told next to nothing about the Second & Third Levels: we learn only that they represent "reduction" and "elimination" of "greed & hatred." The Early Texts say nothing about what these descriptions might mean, or what they imply for the practitioner. These omissions effectively operate as an impassable barrier to progress after First Level. This book aims to provide the guidance that is missing from the Early Texts. It offers an empirical account of the unfolding of Gradual Awakening, together with a scientific hypothesis to explain it, and instructions for realizing it yourself. The hypothesis posits that Gradual Awakening progresses by eliminating the "ego" that develops through the process of self building during infancy and early childhood. The human ego arises from four fundamental misconceptions of reality, the Four Ego Formations. These misconceptions are the source of the ordinary misery of human existence, what the Buddha called dukkha. The Gradual Path unfolds by correcting these four misconceptions, and eliminating the unhappiness they cause. The author's account is resolutely scientific. He sets to one side the supernatural teachings that feature so prominently in the Early Texts. He also ignores their ascetic teachings, asceticism being neither a cause nor an effect of progress in Awakening. In short, this work is intended as a worldly (non-ascetic), secular (non-religious) and scientific (non-supernatural) account of the unfolding of Gradual Awakening, based on the author's own direct experience.