Tense and aspect is grounded in Gustave Guillaume's notion of “chronogenesis,” the staged development of a complex time image. Within this framework, the historical development of the tense and aspect systems of all branches of Indo-European is analyzed with clarity, demonstrating their divergence from a common model. The approach is based on the notions of Descending (moving-world) versus Ascending (moving-ego) Time, with ω-moments as memory and α-moments as imagination. The position of consciousness in relation to these moments is essential for characterizing aspect.