Dadhyane is mentioned eight times in the Rig Veda. He is the illustrious son of the great sage Atharvan who is credited with the number of discoveries including ayurvedic medicines. Dadhyane is also said to be the father of Manu, another significant Vedic seer. He is also remembered as an ardent worshipper of Agni, the fire God. He is claimed to have understood the secret of the birth of Agni as well as that of Bharata.
He is distinguished above all for his association with manu-vidya, the secret of harmony. There is an interesting legend behind this. He is said to have accessed the secret knowledge through his devotion of Indra, who imparted it to him on the condition that Dadhyane would not reveal it to anyone else, warning him that if he did so, he would be beheaded.
The Ashwini Kumars, however, learnt of this, and out of their curiosity to learn the vidya themselves, they approached the seer. When the later told them of the condition, they assured him that they would find a way out by themselves.
Accordingly, they cut off the head of Dadhyane and replaced it with the head of a horse. Thus they got the secret of the vidya disclosed to them through the mouth of the horse. When Indra came to know of it, he rushed to the spot and removed the head of the horse and the Ashwinis go the original head of the seer attached to his body.