Inspiration, Revelation, Insight, Intuition, Ecstasy, Divine Sight and Supreme Bliss are the seven planes of knowledge.
There are four sources of knowledge: instinct, reason, intuition and direct knowledge of Brahman (God) or Brahma-Jnana (knowledge of God).
Instinct When an ant crawls on your right arm, the left hand automatically moves towards the right arm to drive the ant away. The mind does not reason here. When you see a scorpion near your leg, you withdraw the leg automatically. This is called instinctive or automatic movement. As you cross a street, how instinctively you move your body to save yourself from the cars! There is no thought during such kind of mechanical movement.
Instinct is found in animals and birds also. In birds, the ego does not interfere with the free, divine flow and play. Hence the work done by them through their instinct is more perfect than that done by human beings. Have you ever noticed the intricate and exquisite work done by birds in the building of their beautiful nests ?
Reason Reason is higher than instinct and is found only in human beings. It collects facts, generalizes, reasons out from cause to effect, from effect to cause, from premises to conclusions, from propositions to proofs. It concludes, decides and comes to final judgment. It takes you safely to the door of intuition and leaves you there.
Belief, reason, knowledge and faith are the four important psychic processes. First you have belief in a doctor. You go to him for diagnosis and treatment. The doctor makes a thorough examination of you and prescribes certain medicines. You take them. You reason out: “Such and such is the disease. The doctor has given me some iron and iodide. Iron will improve my blood. The iodide will stimulate the lymphatics and absorb the exudation and growth in the liver. So I should take it.”
Then, by a regular and systematic course of these drugs, the disease is cured in a month. You then get knowledge and have perfect faith in the efficacy of the medicine and the proficiency of the doctor. You recommend this doctor and his drugs to your friends so that they too might benefit from his treatment.
Intuition Intuition is personal spiritual experience. The knowledge obtained through the functioning of the causal body (Karana Sarira) is intuition. Sri Aurobindo calls it the Supermind or Supramental Consciousness. There is direct perception of truth, or immediate knowledge through Samadhi or the Superconscious State. You know things in a flash.
Professor Bergson preached about intuition in France to make the people understand that there was a higher source of knowledge than the intellect.
In intuition there is no reasoning process at all. It is direct perception. Intuition transcends reason but does not contradict it. Intellect takes a man to the door of intuition and returns. Intuition is Divya Drishti (divine vision); it is the eye of wisdom. Spiritual flashes and glimpses of truth, inspiration, revelation and spiritual insight come through intuition.
The mind has to be pure for one to know that it is the intuition that is functioning at a particular moment.
Brahma-Jnana
Brahma-Jnana (knowledge of God) is above intuition. It transcends the causal body and is the highest form of knowledge. It is the only Reality.