After Buddhi the next energy in order is the Mind, and the Vaisesika system is based on the idea of its creative character and so Vedanta, Yoga and Vaisesika, based on the character of the Mind and higher energies, understand it aright; while Nyaya and Sankhya, based on the idea of the senses of knowledge and action, understand it only partially and imperfectly.
Vedanta understands the Mind in relation to the character of Prana or the Soul; in Yoga it is examined in relation to Buddhi; in the Vaisesika it is regarded in itself; while Nyaya examines it in the light of the senses of knowledge, and the Sankhya in that of the senses of action and Prakrti or Food.
Mind in Vedanta: Vedanta examines the Mind in relation to Heart-energy, Prana, or the Soul; and so we are told that "from the Heart proceeded the Mind"; that the Mind is fastened to breath or Prana.
Mind in Yoga: Yoga considers the Mind in the light of Buddhi; and so we are told that the Sun is spirit, matter is the Moon (symbolic of Mind). We have already explained that the chief difference between Mind and Buddhi is that the one raises a question and the other solves it; that the one is characterised by doubt and the other by certainty; and that when Buddhi desires anything, it is changed into the Mind.
Mind in the Vaisesika: The Vaisesika examines the Mind in its own character, as the highest creative energy of life. Thus it is said that the Mind is Brahman; that Prajapati created by his Mind Waters and Varuna (Prakrti); that the Mind is the Self; and that the person (purusha or Soul) in the form of the Mind is within the Heart, and is the ruler of all that exists. Then we are told that the Self consists of the Mind and "that a man sees with his Mind. Desire, doubt, faith, memory, shame, fear, all this is Mind".
Mind in Nyaya: Nyaya considers the Mind in the light of the senses of knowledge; and the Mind is often included among the senses, especially in connection with the quarrel of the senses with Prana or breath. Again, we are told that the senses cannot function without the Mind, that when the Mind is absent, the eye does not see, the nose does not smell, the ear does not hear, and the tongue does not taste.
Mind in the Sankhya: The Sankhya deals with the Mind in the light of the senses of action on the one hand and Prakrti or Food on the other; and so it is said that the Mind comes from food, and that the subtlest portion of food is transformed into the Mind; and when the Mind is absent, the hands do not act, the feet do not perceive any movement, nor can we know pleasure or pain, offspring, or joy.