The Ishavasya Upanishad is one of the shortest Upanishads, containing barely 18 verses. In it's brevity, the most sublime knowledge is found, the essence of the Vedas. The Ishavasya Upanishad is significant because of its description of the nature of the Supreme Being - Isha. The manifest world that we perceive, or our experience, is the tip of the iceberg. All that we experience through the senses is a small part of the Universe; most of it is un-manifest. That is full. To understand, we must have an experience of what that is. This is what the Ishavasya Upanishad is about.