According to Osho, the 'secret' of Guru Purnima on Ashadha’s full moon is poetic, not astronomical: the full moon is a metaphor for totality, innocence and luminous presence through which the guru’s wisdom can be reflected; grasping this symbolism—neither dismissing it as fantasy nor mistaking it for fact—opens the heart to the mystery of discipleship.
It’s a symbolic festival: the bright full moon stands for a clear, pure heart that can mirror the teacher’s light.