What Is the Warmth Sign?

The "warmth phase" within the Four Preliminary Practices refers to a state of wisdom attained by consciousness and the manas (mind root). It is a form of cognitive wisdom. Through contemplative investigation by the conscious mind, the manas tentatively accepts the view that the five aggregates and the eighteen elements lack a self. While not yet firmly established, this initial acceptance generates an inner warmth, causing the mind to no longer resist the principle of the non-self of the five aggregates. The warmth phase and the sensation of warmth are not material phenomena; this is a metaphor representing the state and feeling of the mind. "Warmth" signifies the state just before fire is about to ignite—warmth appears first, and then the fire catches. This metaphor illustrates the state of wisdom in the manas, indicating a certain level of understanding of the Dharma and a preliminary acceptance of the principle of the non-self of the five aggregates. Only after this can genuine faith and realization arise.