"The One Vehicle Key," presents a comparative analysis of the Lotus Sutra and the Heart Sutra, arguing that the latter's wisdom of emptiness functions as a provisional teaching within the context of the Lotus Sutra's ultimate doctrine of the One Vehicle. The author asserts that the One Vehicle gathers all Buddhist teachings as skillful means toward universal Buddhahood, which is the via transformativa that follows the Heart Sutra's preparatory via negativa of conceptual dismantling. The essay meticulously contrasts the texts' philosophical frameworks, their distinct approaches to attainment and reality, and critically examines contemporary scholarship regarding the historical dating of both sutras, particularly the evidence suggesting the Heart Sutra originated in China. Finally, the text concludes with a guided meditationthat integrates the core teachings of both sutras into a unified practice using the seven characters of the Odaimoku.