A Buddhist canon or scripture regarded as having been spoken by the Buddha. The chanting of sutras can at times be a form of singing, but more commonly it is done in a rhythmic way in a normal tone of voice. Some sutras are intentionally recited in a monotone. Sutras are chanted as part of most Zen gatherings, whether the occasion is for a special ceremony or regular weekly zazen meeting. One of the best known is the Heart Sutra. A short sutra is often called a gatha.