This restless mind is buddha nature. Because it is so intelligent, therefore it is restless. It is so transparent that we can’t put any patch on it to mask over the irritation—if we do, the irritation still comes through. We can’t hold the irritation back or maintain ego-style comfort anymore. In tantric literature, buddha mind is referred to as a lamp in a vase. If a vase is cracked, the imperfections of the vase can be seen because of the light shining through from inside. In Mahayana literature, a popular analogy refers to enlightened mind as the sun and ego’s security as the clouds that prevent the sun from shining through.
From Ocean of Dharma: The Everyday Wisdom of Chögyam Trungpa, Number 141.