Akshi Upanishad is a minor Upanishad appended to the Krishna Yajurveda. Akshi(meaning Eye) Upanishad, teaches visionary wisdom, and is divided into two parts. Akshi Upanishad mentions the basic requirements needed to reach the seven different stages in Yoga. It also reiterates the importance of AUM (the primordial sound), and equates it with Ultimate God. Akshi Upanishad contains the prayer of sage Sankruthi to Lord Surya which contains the Chakshushmathi Mantra. This is followed by the teaching of Brahma Vidya by Surya.
Ekakshara Upanishad is an Upanishad which deals with the letter 'Om'. This is more of a prayer towards 'Om'.
Garbha Upanishad is from the Krishna Yajur Veda. It explains in detail the processes from the conception of a child in the womb to its birth. Garbha means womb, and there is mention about each stage of development of the fetus. This Upanishad expounds the details of what human consciousness goes through, while it still resides in the womb, in the form of a fetus. The soul trapped within the maternal womb, goes through a state of emotional turmoil, remembering past births and deaths. Garbha Upanishad states that the fetus before birth promises God not to repeat evil deeds but during the process of birth, a force called the 'Vaishnava Prana' touches him, and he forgets his thoughts and prayers. This entails repeating the process of learning and seeking the ultimate truth once again in the life granted.
Pranagnihotra Upanishad is a minor Upanishad which explains how to transform the external ritual of the fire sacrifice into pranagnihotra, "the sacrifice offered in the prana fire" of one's own being.
Svetasvatara Upanishad belongs to the Taittiriya school of the Yajur Veda. Its name is derived from the sage who taught it. It is theistic in character and identifies the Supreme Brahman with Rudra who is conceived as the material and the efficient cause of the world, not only the author of the world but its protector and guide. The elements associated with theism, Personal God and devotion to Him, which are to be met with undoubtedly in the other Upanishads, become prominent in the Svetasvatara Upanishad.
The emphasis is not on Brahman the Absolute, whose complete perfection does not admit of any change or evolution but on the personal Isvara, omniscient and omnipotent who is the manifested Brahma.
Terms which were used by the later Samkhya philosophy occur in the Upanishad, but the dualism of the Samkhya, purusa and prakrti, is overcome. Nature or pradhana, is not an independent entity but belongs to the self of the Divine, devatma-sakti. God is the mayin, the maker of the world which is maya or made by him. The Upanishad teaches the unity of the souls and world in the one Supreme Reality. The Upanishad is an attempt to reconcile the different philosophical and religious views, which prevailed at the time of its composition.
A special feature is the prominent conception of Devotion or Bhakti. In other Upanishads, the concept of Bhakti is indirectly voiced in the form of Upasana, but here, leaving no room for guesswork, it is explicitly mentioned. The word para-bhakti is explicitly used at the end of the sixth chapter. There are many words which voice submission to God or Brahman (words such as Sharanam, Prapadye, etc.). This concept of devotion later found profound expression in the Bhakti Sutras and other treatises on Bhakti.
The second special of this Upanishad lies in its giving importance to the form (fullness or murtitva) of God, where Brahman is often described as formless in other important upanishads. Since it is difficult to concentrate the mind on and/or show devotion to a formless Brahman, the Shvetashvatara Upanshad ascribes various forms to God. While expounding on devotion, it also describes various characteristics or manifestations of God, such as mentioning that he has knowledge and power. This Upanishad also presents God as the creator and sustainer of the universe and, while describing various powers of God, drives home the point with similes such as God having thousands of heads Sahasra-sheersha - to denote God's endless knowledge, thousands of eyes - to denote God as the universal witness for everything going on in the universe and God's having thousands of feet - to indicate his omnipresence. This Upanishad mentions that God or Parama Purusha is shining in his glory beyond the darkness of ignorance or Tamas. God controls the material energies of the universe through his characteristic Maya or illusion of the world, but God is not bound by his Maya as humans are, because he is its controller and is capable of giving salvation to human beings.
Normally, Upanishads are sources of serious philosophical thought, but this Upanishad differs from other Upanishads by explaining the same principles in a simple, easy-going and poetic way. Wherever the sage Shvetashvatara has his independent hymns, he sees them in a beautiful, heart-catching, poetic way. He is not only a seer of Mantras, but also a poet from his heart. Here are few examples.
While trying to describe the omnipresence of Brahman, hymn 4.2 says,
"You are woman; you are man; you are boy and you are girl; you are the shivering old man helped by a stick; you are born in the form of this world."
Hymn 4.4 says
"You are the blue butterfly, the green-eyed parrot and the lightning cloud. You are the seasons and the seas. You are the one without any beginning; you are omnipresent; all the worlds are born out of you."
Sariraka Upanishad talks about the different aspects of the human body, including states of knowledge. The body is a combination of the five elements like earth. What is hard is earth, what is liquid is water, what is hot is fire, what moves is air, what is porous is space. The organs of sense are ear etc.: the ear is in the sky (space), the sense of touch (skin) is in the air, the eye in the fire, tongue in water, smell in earth. Thus for the senses sound etc., are the objects. The organs of action are: tongue, hands, feet, arms and genitals. Their objects are: speech, catching, walking, voiding and joy. These have arisen from earth etc., respectively.
Mind, Intellect, Egoism and Self-conscious mind are the four inner senses. Their scopes are volition and doubt, determination, affection, decision. The mind is at the tip of the neck, intellect at the face, egoism at the heart, self-conscious mind at the navel.
Bone, skin, nerves, hair, flesh are parts of earth; urine, phlegm, blood, semen are of water; hunger, thirst, laziness, delusion and sex of fire; circulation, bursting, movement of the eye etc., of air; lust, anger, greed, delusion and fear are of ether.
Earth's attributes are Sound, Touch, Form, Taste and Smell; of water: sound, touch, form and taste; of fire are: sound, touch and form; of air: sound and touch; of ether: sound only.
Non-violence, truth, non-theft, continence and non-possession, absence of anger, service to elders, cleanliness, contentment and honesty, non-conceit, candour, faith and non-injury - are the qualities (effects) of Sattva. I am the doer, enjoyer, speaker, am conceited - these are of Rajas. Sleep, laziness, delusion, attachment, sex and theft - these are of Tamas. The person of Sattva is above, of Rajas is in the middle and of Tamas, low. Right knowledge is Sattvika; of rituals, Rajasa; blindness, Tamasa.
First the waking state rests on the five organs of sense, the five of action and the four inner senses (being active). Dream depends on the four inner senses only; dreamless sleep has only mind as active instrument; the fourth state has only the soul (active). The knower is the empirical self, other than the supreme, stationed between awareness (of object) and indifference (to them).
The five organs of sense and action with the five vital airs, the mind and intellect, go to make the Lingasarira. Mind, intellect, self-conscious principle, earth etc., are the eight Prakritis. There are sixteen others; the transformations of ear, skin, eyes, tongue, and nose; arms, genitals, hands, feet, vocal organ; sound, touch, form, taste and smell. The twenty-three are the Tattvas (eternal verities) relating to Prakriti. The twenty-fourth is the Avyakta, the chief (Tattva). That which completes the group as the twenty-fifth is the Purusha (Self).