The book attempts to present a new vision or view in the world of knowing. The query it poses is, What is it that we know? Our spontaneous assumption is, what we know is real, the existent as it is or exists. The attempt here is to find how far our claim that what we know is real or that what is there and what we know is the same is true. If not, what is it that we know? The theory of relativity claims, on the scientific evidence, that we do not know what is real because the real—that which is—changes. Einstein's theory of relativity throws the onus of relativity on the nature of the real. This attempt tries to find the cause of relativity, if there are any. One may be surprised to find a new vision of what we know and the cause of relative nature of knowledge.