One who cannot conceive that he is more than his physical body, will be unable to gain knowledge. While he will gain the experience, he will miss the totality of the experience, and fail to gain the knowledge the experience was designed to bring.
Beings who are unable, unwilling, or simply choose not to see themselves beyond their thoughts, will fail to gain wisdom, insight, or understanding of him self, others, or the world.
When one does not see, accept or acknowledge the spiritual part of him or her self, and thus stays separate from his/her higher self, knowledge cannot be gained.
If we can conceive that our physical eyes cannot see or experience visually another continent, the mind knows it exists, so therefore the being can one day plan to visit that continent. But if the being knows nothing of this continent, it will have no knowledge of it, and will never experience the wonders of that continent.
And so it is with the spiritual part of man. If a being refuses to accept he/she has a higher, wiser self, its experience will be just that--an experience--void of the ability to see past his/her physicality, and that being will lack knowledge, insight, and understanding.
It is like living a life with only one half of the body, one half of the mind, and one half of the brain...