The origin and early evolution of life may have been shaped by interactions with environmental rhythms. This paper presents the Tidal–Thermal Synchronization Theory (TEXTBFTTST), grounded in a two-stage evolutionary hypothesis wherein primordial life, born at deep-sea hydrothermal vents, first adapted to thermal and tidal rhythms, and subsequently adapted to the solar rhythm upon colonizing shallow seas. Key Epistemological Positioning: TTST posits that terrestrial carbon-based life was nurtured by two Gifts (in the sense of Gifted): 1. First Gift (Intrinsic Necessity): Life may have been intrinsically given a stable 24-hour periodicity as an inherent solution, emerging from its own physicochemical properties. 2. Second Gift (Environmental Contingency): The very planet upon which life emerged also underwent a rare evolutionary history, with Earth’s rotation period converging from an initial ∼18 h toward the current 24 h—a singular gift from planetary mechanics. This paper argues that the period-determining mechanism of the transcription–translation feedback loop (TEXTBFTTFL), which lies at the heart of the modern circadian clock, constitutes the material evidence of these dual gifts. Keywords: circadian rhythms, origin of life, hydrothermal vents, two-stage evolution, giftedness, environmental rhythms, TTFL, stochastic stability, Snowball Earth