Swami Abhedananda 
Vedanta Philosophy: Self‑Knowledge. Vol VI 

In this age of scepticism and materialism few people care to know their real Self, which is Divine and immortal. But the knowledge of the true Self has always been the principal theme of the philosophy and religion of Vedanta. Even in its most ancient writings, the Upanishads, which form portions of the Vedic Scriptures, we find how earnestly Self‑knowledge or Atma‑jnana was sought after and extolled. The great inspired seers mentioned in these Upanishads discovered and taught that knowledge of the Self lies at the root of all knowledge, whether of science, philosophy or religion. Every sincere seeker after knowledge, therefore, who desires intellectual, moral or spiritual development, must first learn to discriminate between spirit and matter, soul and body, and then realize the all‑knowing Divine Self who is the eternal foundation of the universe.