Let us try to see absolute reality from the perspective of space and time. If an entity does not last long, we do not value it. This is true of our dreams. Since the experiences of a waking state last longer, it has more credibility for us. So, we can say that longevity is a measure of reality. Likewise, if something occupies a limited space, it can affect a limited space and has limited significance. Reality should have far-reaching significance. Essentially, the reality is eternal and all-pervading. In Vedanta, reality does not change with space and time. While interpreting the Mandukya Upanishad, Gaudapada lays down the fundamental principles of non-dual philosophy. Starting with the example of dreams, he shows that our experiences in a waking state are also not real. And, if these experiences are not real, we have to discard them in our search for reality. As one cannot discard himself, we know reality if we remove all obstructions. Later, Shankara used this groundwork in his timeless commentaries.