The word gabhīra-rayaḥ, or “imperceptible speed and power,” is significant. We observe that by the laws of nature all material things, including our own bodies, gradually disintegrate. Although we can perceive the long-term results of this aging process, we cannot experience the process itself. For example, no one can feel how his hair or fingernails are growing. We perceive the cumulative result of their growth, but from moment to moment we cannot experience it. Similarly, a house gradually decays until it is demolished. From moment to moment we cannot perceive exactly how this is happening, but in the course of longer intervals of time we can actually see the deterioration of the house. In other words, we can experience the results or manifestations of aging and deterioration, but as it is taking place the process itself is imperceptible. This is the wonderful potency of the Supreme Personality of Godhead in His form of time.
Source: A.C. Bhaktivedanta Swami Prabhupada (2014 edition), “Srimad Bhagavatam”, Eleventh Canto, Chapter 06 – Text 15