The Diamond Sutra has fascinated Buddhists for centuries because of its insights into dualism and illusion; the "diamond" can cut through any obstacle on the road to enlightenment. In the sūtra, the Buddha has finished his daily walk with the monks to gather offerings of food, and he sits down to rest. Elder Subhūti comes forth and asks the Buddha a question. What follows is a dialogue regarding the nature of perception. The Buddha often uses paradoxical phrases such as, "What is called the highest teaching is not the highest teaching". The Buddha is generally thought to be trying to help Subhūti unlearn his preconceived, limited notions of the nature of reality and enlightenment. Emphasizing that all forms, thoughts and conceptions are ultimately illusory, he teaches that true enlightenment cannot be grasped through them; they must be set aside.