As against this, there is a parallel mode of enquiry, into existence or otherwise, of a permanent subjective entity behind the body-mind complex. This is called atman (the Self or the soul).
Is this atman one or many? Is it finite in size or infinite? Is it identical with Brahman or different? Though the Upanishads discuss these questions, there does not appear to be a single answer. Different viewpoints seem to exist. However, the orthodox Vedantic schools present only one view as the right one to the exclusion of the others.
The basic cause of the universe, the cause of all causes, is called ‘Brahman’ by the Upanishads. Atman, Sat, Akshara. Akasa and Bhuma are the other appellations used for this Brahman. The world rises out of him, is supported by him and gets dissolved back into him. He is omniscient, omnipotent and omnipresent. He is greater than the greatest, smaller than the smallest and is also the inmost self of all. He is immanent in this world even as salt is, in saline water. He is beyond all wants and limitations. He is the lord as well as the substratum of the whole creation. He sees, hears and knows although none can see or hear or know him. He is the very personification of all the great virtues to their perfection. It is he who responds to the prayers of his votaries and grants them whatever they seek. He is the ultimate goal of all.
To facilitate meditation upon him, the Upanishads sometimes describe him as a purusha (the divine being in the human form), bright and brilliant, of golden hue, with all parts of his body of golden colour and his eyes resembling a fully bloomed red lotus. Fire is his head, the sun and the moon are his eyes, the quarters are his ears, the Vedas are his speech and the earth is his feet. Sometimes he is also described as having thousand heads, thousand eyes and thousand feet, thereby stressing his omnipresent cosmic form. This form recommended for meditation is the Aupanishada-Purusha (the Being described in the Upanishads).