The Buddha brings about a positive vibration and purifies the mind by creating the serenity to overcome negative emotions.
The Bhumisparsha Mudra is a gesture of taking the earth as witness "Gesture of touching the earth" This was a gesture of Gautama Buddha when he summoned the Earth to witness his enlightenment and his worthiness as a Buddha at both Gaya as he thwarted the temptations of the demon Mara.
