The Vedas, as the Hindus say, are eternal. We now understand what they mean by their being eternal, i.e. that the laws have neither beginning nor end, just as nature has neither beginning nor end. Earth after earth, system after system, will evolve, run for a certain time, and then dissolve back again into chaos; but the universe remains the same. Millions and millions of systems are being born, while millions are being destroyed.
The universe remains the same. The beginning and the end of time can be told as regards a certain planet; but as regards the universe, time has no meaning at all. So are the laws of nature, the physical laws, the mental laws, the spiritual laws. Without beginning and without end are they; and it is within a few years, comparatively speaking, a few thousand years at best, that man has tried to reveal them. The infinite mass remains before us. Therefore the one great lesson that we learn from the Vedas, at the start, is that religion has just begun. The infinite ocean of spiritual truth lies before us to be worked on, to be discovered, to be brought into our lives. The world has seen thousands of prophets, and the world has yet to see millions. (VI, 9)
Only recently modern science has come to understand a little bit of the eternality of the cosmos. On the other hand, our great seers, based on their inner knowledge have described cosmos as infinite, indescribable and unexplorable. The secret of the eternal relevance of Indian spirituality is due to the fact that we have always held fast to the Eternal Truth. The great rishis of Upanishads were pointing to this Eternal Truth when they addressed humanity as ‘Children of Immortality’