The eye of harmony is a power source that makes time travel possible. It is a "contained" black hole that drives the TARDIS [time and relative dimensions in space], an imaginary trans-dimensional vessel . It's clear perceptions see the bigger picture, and the patterns embedded in what we call time. Invoking the ancient formulas, the aspirant makes mental contact with the spirits of the past and future, getting glimpses of their worlds, all simultaneously existing in the harmonious now, protected like the pupil of the cosmic eye.