Phases
Through the ages, we used celestial bodies to measure time. Before the clock and calendar invention, human beings relied heavily on the sun's position and the moon's phase for measuring time. Our lives are also stretched across a time period. We use our earthly bodies to measure time as well. We measure our time in this life through different phases, like childhood, puberty, adulthood, and old age. Like the moon goes through different phases, we also go through different phases.
This entire experience we call life is also one of our soul's phases, just a small part of the bigger picture. At the end of the road, we'll find that which we bought with earthly time, that which we bought with earthly phase. The analogy can be found in the Qur'an, where God informs us about our phases.