manuals, entitled Closely Stringed Pearls. After describing the visualization of the three channels, the text outlines the four chakras which are to be visualized along the central channel with various spokes radiating out of each chakra like an open umbrella. The four chakras described by Gampopa are: At the navel, there is the emanation-cakra with 64 spokes. At the heart, there is the Dharmacakra with 8 spokes. In the throat, there is the enjoyment-cakra with 16 spokes. At the top of the head, there is the great-bliss-cakra with 32 spokes. Kragh outlines the practice as follows: Another meditation manual by Gampopa also mentions a practice that relies on visualizing a drop (thig le, *bindu) between the eyebrows. This bindu descends and ascends through the central channel, spreading a sensation of bliss-emptiness along the way. Regarding post-meditation, the yogi is "instructed to train in experiencing all sensory impressions as blissful and to maintain a constant sense of inner heat and the soothing, cooling bliss of the descending bodhicitta. It is said that the experience of everything as being blissful will automatically give rise to the experience of non-thought (mi rtog pa, nirvikalpa)." Gelug lineage In Tsongkhapa's system, inner heat is the foundation stone for the whole six dharmas (along with meditation on emptiness). Every time one practices one of these six dharmas, one must first generate inner heat, along with the four blisses and merge this with meditation on emptiness. Once mastered, tummo is then applied to the practice of illusory body, and based on illusory body yoga, one practices radiance/clear light yoga. Tsongkhapa's commentary The Three Inspirations, divides the practice of inner heat into three main components: Meditating on the channels; one first visualizes the three channels (right is red, left is white and central channel is blue) and then the four chakras at the crown (multicolored with 32 petals), throat (red with 16 petals), heart (white with 6 petals) and below the navel (red with 64 petals). One fixes the mind on each chakra and with practice they become increasingly clear. If this is too difficult, one can just meditate on the channels first, or on the point where they meet below the navel. The goal is to achieve a stable clarity of the radiant appearance of the channels and chakras for a prolonged period of time. One can also join this practice with the vase breathing exercise (i.e.