The view put forth by the Sankhya philosophers, that an external and internal world exists in mutual independence, is contrary to thought and experience--is, in fact, unthinkable. We know no external world: we have never had any experience outside the region of our own consciousness; yet what is regarded as external to the individual consciousness is not _Maya_, as is taught in some of the Upanishads, and maintained by later philosophers. This external world as a fact of consciousness is as real as that consciousness and as the individual mind which makes mental experience possible, and is the great All, of which the individual mind is the working and manifestation. THE RELATION OF BRAHMAN TO ELEMENTS AND THE SOUL Are the elementary substances (ether, air, etc) co-eternal, with Brahman, or do they issue from him? It can be shown, and is shown, that one elementary substance proceeds from another (_e.g._, air from ether), and that in the last resort all such substances have come forth from Brahman, who has not only produced them, but also guided and effected their evolution. The individual soul is, according to the scriptures [Vedas and Upanishads], eternal and permanent, and has not been produced by Brahman; who is, however, as noted, the producer of the elementary substances. Like Brahman himself, the individual soul is uncreated and eternal. What is in time and belongs to time is the connection of the soul with the conditions of space and time. This is the interpretation given by Sankara. Ramanuga, however, holds that the soul is a creature of Brahman, though an eternal one, it having existed ever as a mode of the great All [compare the doctrine of the eternal procession of the Son]. WHAT IS SOUL? What is soul? It is _gna_, or knowledge. [The etymology of both these latter words is identical--compare Greek _gnosco_, etc.] This means, according to Sankara, that knowledge is of the very essence of soul, and not a mere attribute of it. The soul is not merely a knower (_gnatri_), but it is knowledge. Ramanuga, on the other hand, explains that the knowledge spoken of in this Sutra means "the knower"; that the soul is not knowledge, but that which can and does know. Is the soul limited in size, and capable, therefore, of occupying but a restricted space? Or is it, on the contrary, omnipresent? Sankara maintains that the Sutra in question teaches the latter; the soul is everywhere. Ramanuga makes the same Sutra teach the very contrary. As a matter of fact, the Sutra in question seems to teach both these contradictory doctrines, perhaps because it registers different traditions. Sankara, however, explains further on that as long as the soul is passing through the changes involved in Samsara [= transmigration] it is limited and local, but on reaching Brahmanhood it becomes omnipresent. In this way the great commentator seeks to reconcile teaching apparently contradictory in this Sutra.