When we begin to explore the concept of there being a higher evolutionary stage beyond the mental level, we then must necessarily take up the question of how we can identify, recognise and confirm this. We cannot ask them mind necessarily to do so, as it tends to doubt the veracity and validity of experiences which cannot be viewed externally and confirmed systematically. Powers beyond the mind tend to raise substantial skepticism in the realms of the mind. At the same time, when a large number of people over time and throughout the world report similar types of experiences which cannot be easily classified or understood by the mind, we can and should be able to take notice.
While such experiences are reported widely in numerous traditions yet it is the Indian tradition of Yoga which has actually tried to explore, classify and categorize these experiences into a consistent and coherent body of knowledge. The Upanishads in particular have organized this information. The Indian tradition also holds out that the evolutionary progression has manifested these higher stages previously, which have subsequently degenerated and are now being re-discovered.
The Taittiriya Upanishad stands out as a particularly useful text in this regard, as it sets forth clearly the 5 “sheaths” which make up the human experience, starting with the most external, the “food sheath” (the physical being) and moving toward more and more subtle levels which include the vital sheath, the mental sheath, the knowledge sheath and the bliss sheath. Sri Aurobindo organizes these into three “bodies”, the gross physical body consisting of the physical and vital sheathes, the subtle body, consisting of the mental sheath, and the causal body consisting of the knowledge and bliss sheaths.
Sri Aurobindo clarifies the meaning of the “knowledge” and “bliss” sheaths: “But this knowledge is not a systematised result of mental questionings and reasonings, not a temporary arrangement of conclusions and opinions in the terms of the highest probability, but rather a pure self-existent and self-luminous Truth. And this bliss is not a supreme pleasure of the heart and sensations with the experience of pain and sorrow as its background, but a delight also self-existent and independent of objects and particular experiences, a self-delight which is the very nature, the very stuff, as it were, of a transcendent and infinite experience.”
The experiences that led to these statements and conclusions show us, according to the sages and seers who have recorded and organized this information, a reality that exceeds the mental framework which is considered to be the current peak of the human capacity. They are called “causal body” because they take on and utilize the subtle and gross body to implement the intention of the Divine in the manifestation. Rather than the body/mind creating the spiritual truths, as Western psychology has held out, it is the spiritual truths that have created the body/mind nexus.
Sri Aurobindo, The Synthesis of Yoga, Introduction: The Conditions of the Synthesis, Chapter 2, The Three Steps of Nature, pp. 11-12