詳しいガイド（英語）
Meaning and tradition
Dharmachakra is Sanskrit for the wheel of the Dharma, the Buddhist teaching. The gesture belongs to Buddhist iconography: statues and paintings show the Buddha with both hands at the chest forming two circles that touch, representing the first sermon in which he set the wheel of the teaching turning. It is a gesture seen in depictions of the Buddha, not a health mudra from the classical hatha yoga texts.
Because it uses both hands symmetrically and shows two thumb and index circles together, it is read in modern yoga as balancing all five elements rather than emphasizing one.
How to practice
Sit in Easy Pose or Lotus Pose. Bring both hands to the chest, join each thumb and index fingertip into a circle, then turn the right palm out and the left palm in so the two circles touch. Keep the other fingers extended and soft.
Breathe slowly through the nose. Dirga Breath gives a steady rhythm. Hold for a few breaths up to five minutes, then lower the hands to the lap.
Tips and common mistakes
Keep the elbows close to the body and the shoulders down. Hands held far in front tire the shoulders quickly.
Know the neighbors. Unlike Vitarka Mudra, which raises only the right hand with the left in the lap, here both hands are at the chest and the two circles touch. Unlike Chin Mudra, where the hands rest on the knees with a single circle each, here the hands are raised and the circles meet. Unlike Hakini Mudra, where all the fingertips of one hand touch those of the other, here only the thumb and index fingertips form circles and the palms face different ways.
Keep the circles soft rather than pinching, and keep the two hands level.
Tradition vs. evidence
The meaning of this gesture is religious and symbolic. No research shows that it balances the elements or improves the mind. What is defensible is that a symmetrical, effortless hand position gives attention something to settle on and pairs well with slow breathing.