“Delusion refers to belief in something that contradicts reality. In Buddhism, delusion is … a lack of awareness of the true nature or Buddha nature of things, or of the true meaning of existence. ”
According to the Buddhist outlook, we are deluded by our senses– among which intellect (discriminating, discursive thought) is included as a sixth sense.
Consciousness, attached to the senses, leads us into error by causing us to take the world of appearances for the world of reality, whereas in fact it is only a limited and fleeting aspect of reality.” (The Shambhala Dictionary of Buddhism and Zen.)