"… in the tantric and vedic traditions human life is much sought after, even by those who have attained divinity, because only man can know the creator. In that sense the human birth is considered to be most valuable.
According to tantra, the universal consciousness descends towards manifestation as individual consciousness, assuming the states knows and buddhi, chitta, ahamkara, and man as. Buddhi represents the higher intellect with its activity of viveka, or discrimination, and sadvichara, or right thinking. Manas is the lower mind with its characteristic activity of sankalpa and vikalpa, or thought and counter thought. Chitta, or memory, is the storehouse of past actions in the form of samskaras or archetypes. Ahamkara, or ego, is the notion of self-existence, conditioned by the above three.
This is the arc of avaroha, or the descent of the dynamic universal consciousness into human life. It is only at the human stage of evolution that unmesha or aroha, the ascent towards higher life, is possible. Inner realization dawns when manas, buddhi, chitta, and ahamkara are dissolved into universal consciousness through the medium of shakti, or energy. This is the highest yajna, or sacrifice, man can offs. Other forms of life do not have this privilege because they do not have these four aspects, which are collectively known as antahkarana, or the inner instrument."
Sri Vijnana Bhairava Tantra - Swami Satyasangananda Saraswati