A clue to the structure of the world is given us by an investigation into the nature of causation and the resultant discovery that the effect is non-different from the cause. If the world is an effect, it must be non-different from Brahman, which is its cause. Individualistic perception is accustomed to make a distinction between effect and cause, between the world and reality. That the world is transitory is a fact borne in on us by its constant nature, its subjection to evolution and involution and its tendency to point to a being that is beyond itself. The things of the world are not ends in themselves, a fact which discloses itself in the constant urge that is seen in individuals to outgrow their limitations and aspire for a higher realisation. The contents of the world do not seem ultimately to satisfy any aspiring soul. The effect always yearns to unite itself to its cause, for its reality is not in itself but in its cause. The world can never be happy by itself, for its happiness is in its reality which is Brahman. The misery of the world is but the consequence of the erroneous consciousness that the effect is different from the cause, that the world lies outside Brahman. It is this error that is responsible for the unrest of the world and of the unceasing struggle of everyone to reach out to some permanent happiness. The relation between Brahman and the world cannot be strictly one of cause and effect. We cannot conceive of cause and effect without imagining at the same time a difference between the two. As Brahman is the sole existence, there can be nothing second to it, and if there is nothing other than it, there can be no effect outside it. The world is either one with Brahman or different from it. In the former case, there would be no world, and in the latter, no causation, and so, again, no world. That the world is a creation of Brahman is not an ontological truth but an empirical necessity arising out of the habit of the mind to seek a cause for every effect. The scriptures declare that there is freedom from the bondage of the world, but this freedom would be impossible if the world were a real effect. The highest bliss can be only in the knowledge of the non-difference of the world from Brahman.

The appearance of Brahman as the world is not analogous to the transformation of a cause into its effect. Brahman does not become the world but appears as the world. The rope never transforms itself into a snake, even when it appears to have all the characteristics of the snake, owing to erroneous cognition. The hypothesis that Brahman transforms itself into the world is logically unacceptable, for whatever is subject to transformation of essence is liable to destruction. The eternal Brahman does not really become the world. Real change of a substance is tantamount to its annihilation. The Upanishads proclaim that Brahman is the supreme ideal of life, and so its annihilation can never be conceived. The world is not a Parinama (modification) but a Vivarta (appearance) of Brahman. Brahman appears as the world, not in the manner of milk turning into curd, but of a rope appearing as a snake. Only the Vivarta view of manifestation can satisfactorily support the validity of scriptural statements, and also stand the test of reason. If Brahman has already become the world by a process of transformation of its being, then there is no Brahman whose realisation we can aspire for, and there is no Moksha or freedom of the soul from the bondage of Samsara. In the Vivarta view of the manifestation of the world, there is no such inconsistency involved, for, on this view, an effect appears on the substratum of the cause without there being an actual change in the being of the cause. The appearance of the world has to be attributed to wrong knowledge and not to an actual modification of Brahman.

The change of forms that we observe is not a change of reality. The substance remains unchanged and continues in spite of the appearance of the change of forms that takes place on it as its basis. The substance cannot be destroyed in the process of the change of its qualities or forms. In all change, the existence of a consciousness that knows all change, but does not itself get involved in change, has to be admitted. If even the consciousness of change were to change, there would be no such thing as consciousness of change. Change implies the changeless; the impermanent is known on the ground of the permanent. And if cause and effect are identical, even this change cannot be real. Change becomes an appearance, a phenomenon necessary and valid for an empirical individual, but inadmissible in reality. There is a logical contradiction involved in the non-acceptance of a changeless reality behind change and the acceptance, at the same time, of the reality of change. If change is to be real, reality ought to change; but nothing that changes can be ultimately real. Brahman which does not change is real, and the world which changes is unreal. The apparent existence of the world is borrowed from the being of Brahman, bereft of which the world is nothing.

In our concept of the world are included the different degrees or grades of objective reality that presents itself to our empirical consciousness. The world is certainly not existent like Brahman, for it is subject to change and transcendence. It is also not non-existent like a human horn, for it appears to our consciousness. The term world includes also the objects seen in illusions and dreams. But the world, as it is commonly understood, consists of the objects of waking experience. The waking world has a practical reality that appears to have a higher workable value than the experiences in illusions and dreams. Illusory perceptions and dream phenomena have an apparent existence (Pratibhasikasatta), while the world of waking has an empirical existence (Vyavaharikasatta). Transcending these lower forms of existence is absolute existence (Paramarthikasatta) or Brahman. The world is real as non-different from Brahman, but unreal as consisting of particular names and forms. In none of the degrees in which it manifests itself can the world be ever denied, but has to be accepted as valid in its varying expressions of reality. It is real when it is experienced but unreal when contradicted in a higher consciousness.

The difference between Maya and Avidya that is recognised in the Vedanta explains the distinction between metaphysical idealism and subjective idealism. Maya is the substance out of which the whole world is manifested, the common ground of the expression of forms that are valid for all individuals experiencing them. Maya has an objective existence; it is the cause of even the internal organ (Antahkarana), the principle constituting the individuality of an individual. Avidya, on the other hand, is subjective and private, not universal and necessary for everyone, but restricted to different individuals. The world of Avidya is different from the world of Maya. This important feature is brought out in the famous distinction that is made between Jivasrishti and Isvarasrishti. Jiva is the experiencing individual and Isvara is the immanent intelligence of the universe. Isvarasrishti is the world of Maya, equally applicable to all percipients. But Jivasrishti is the world of Avidya, the plane of subjective relations and reactions abstracted from the creation of Isvara. The Jiva is a part of Isvara, and the body of the Jiva is one among the objects of the world projected by Maya which is the principle that defines Isvara. The objects of sense-perception are, therefore, not mere ideas or fancies in the mind of the subject. They are objective facts, as real as any knowing subject. The objects are different from the knowledge we have of them, for the knowledge of objects is on par with the reality of their forms. The structure of knowledge is determined by the form of the object. Perception is different from memory and imagination, because their objects are different. There is an immediacy of presentation in actual perception, but the objects of memory and imagination are mediate and remote. What is known merely to ideas is differentiated by us from what is known by the senses. This also accounts for the distinction made between waking and dream, notwithstanding the similarity of the framework in which experience is given to us in both these states. Dream and waking are different in the quality of knowledge that is manifest in them, though the mould in which experience is cast is the same in both the states. The subject and the object are always of the same degree of reality as far as the particular experience confined to them is concerned. The Vedanta theory of knowledge is a radical realism inasmuch as it accepts the outside world as independent of the knowledge which the subject has of it. But the question as to the ultimate nature of the objects of knowledge is a different thing altogether. An object may be independent of the mind which perceives it, and yet it may not be material in nature. Though the Vedanta holds that objects are extra-mental in so far as their relation to the subject is concerned, it recognises the ideality of all things in general in relation to the cosmic mind of Isvara. If the objects of the world are not contained in our minds, they are contained in the mind of God. This is the metaphysical idealism of the Vedanta as opposed to subjective idealism. The objects are essentially phases of consciousness, they are Vishayachaitanya. The reality behind both the subject and the object is Brahmachaitanya or the absolute consciousness.

While commenting on the Brahmasutras, dealing with the refutation of the Buddhist idealists, Swami Sivananda touches the point of difference between materialism and subjectivism on the one hand and a higher absolutism on the other. The Buddhist idealists have advanced sufficiently strong arguments against the materialist conception of the world. The existence of matter independent of knowing minds cannot be established. Matter that has no relation to mind is not known to exist. But the position of the Buddhist idealist, as it is generally understood, is not completely acceptable. It cannot be said that the external world is entirely non-existent, for, if this were the case, even the projection of the internal ideas externally would not be possible, or even conceivable. That there is an appearance outside shows that there is a reality behind it. That the world appears to consciousness intimates to us the existence of a changeless ground, albeit invisible to the senses. A non-existent world cannot be sensed or felt in any way. Even if we are to suppose that consciousness alone appears as an external object, we cannot admit that this appearance is possible without a reality outside, for the very possibility of the externalisation of consciousness proves that there is something outside not directly perceived by the senses. Setting aside the view that the world of sense-perception is totally non-existent as logically untenable, we may admit that the world, at least in one sense, is unreal like dream. But this analogy cannot be stretched too far, for the world of waking life is known to be like dream only under certain conditions and not in all respects. The structure of knowledge is the same in waking as well as in dream. In both the states, knowledge is characterised by space, time, the idea of materiality of objects, motion, change, causation and the presented nature of things. Further, as dream is contradicted in waking, the waking world is contradicted in the Atman. We cannot, however, deny that the order of the manifestation of knowledge in dream is different from that in waking, for we are all aware of it instinctively. This distinction has to be clearly understood if we are to have a correct grasp of the sense in which the Vedanta is called an idealistic philosophy. It is a realism epistemologically, but a spiritualistic non-dualism metaphysically. It does not deny the world that is known in any state of consciousness, but it recognises the highest truth of the contradiction of all relative phenomena in Brahman, which alone stands as the ultimately non-contradictable principle. The objection of Prakashananda in his Siddhanta-muktavali that, as dreams are manifestations of consciousness without any real objects underlying them, though they reveal the distinction of subject and object, the world of waking consciousness is devoid of a real content, loses its force unless the relation between dream and waking is understood in the manner pointed out above.

Swami Sivananda distinguishes between two phases of the universe: the phenomenon and the illusory, the empirical and the apparent, the objective and the subjective. The objective universe is physical, while the subjective is psychical. By the word universe what we really mean is the experience of certain objective conditions. Both the physical and psychical experiences can be grouped under the general category of experience. Experience, again, is a term used to denote the awareness of a content in a knowing subject. This content appears as physical in the waking state and psychical in dream, though at the time of the experience of dream, the contents put on the character of physical entities. A comparative study of dream and waking would give us a clue to the relation between the world and God, between the relative and the Absolute. We usually take it for granted that the entities that we perceive in the waking state are physical, just as in dream, too, we take all percepts as nothing short of physical objects. The same analogy may be applied to our world-experience in the waking state in relation to the Absolute. As on waking one feels that the space, time and matter perceived in dream are comprehended in the waking consciousness, the world of waking life is known to be transcended, together with the waking subject, in a consciousness that rises above all existence and essence known to man.

On a careful scrutiny, another important factor will be seen to characterise our experience in waking as well as in dream. When the waking subject perceives an object, a twofold consciousness is found to be involved in it: a consciousness of the presence of a physical object, a physical state or condition, and a consciousness of the particular relation that the object bears to the subject. One does not merely see an object, but sees it also as having some relation to oneself. One likes it or does not like it, or is indifferent towards it. It is ‘mine’ or ‘not mine’, good or bad, pleasurable or painful, necessary or unnecessary, and so on. In fact, it is found that it is hard for one to have a consciousness of an object without at the same time involving a personal relation that obtains in regard to it. Now, this latter aspect of experience, viz., the consciousness of a relation, does not belong to the object, and so it is not an empirical reality. It is a projection from the subject itself, a reaction to the manner in which the object presents itself to the subject or is taken to exist in relation to the subject. The physical object is always seen to possess a greater reality than the psychical relation. It is this individualistic relation that constitutes all bondage. We have, thus, a complicated structure before us, which we call the world.

A beautiful illustration is given by Plato, in his Republic, of the general character of the world of sense-perception. Book VII of this great work begins with the famous description of the cave, which may be briefly stated as follows:

And now let me show in a figure how far human nature is enlightened or unenlightened:—Imagine human beings living in an underground den, which has an opening towards light, through which light reaches all along the den. Here these persons have been living from their childhood, their legs and necks chained, so that they cannot move, but can only see things in front of them, they being prevented by the chains from turning their heads round. Above and behind them a fire is blazing at a distance, and between the fire and the prisoners there is a raised way. There is also a low wall built along the way, like the screen which marionette players have before them. Men pass along the wall, carrying with them vessels, statues, figures of animals, stones and various other materials, which appear over the wall as shadows. And these inside the cave see only their own shadows, or the shadows of one another, which the fire throws on the wall which is opposite to the cave. And of the objects which are being carried, in like manner, they see only shadows. And if they were able to converse with one another, would they not suppose that they were addressing what was actually before them? And suppose, further, that the prison produced an echo of sounds that came from the other side. Would they not be then sure to fancy, when one of the passers-by spoke, that the voice which they heard came from the moving shadow? To them the truth would be literally nothing but the shadows of substances.

And now, again, see what will naturally follow if the prisoners were released and disabused of their error. At first, when any of them is liberated and enabled suddenly to stand up and turn his neck round and walk and look towards the light, he will suffer sharp pains. The glare will distress him, and he will be unable to see the realities of which, in his former state, he had seen the shadows. And imagine someone telling him that what he saw before was a shadow and that now, as his eye is turned towards an existence of greater substantiality, he has a clearer vision,—what will be his reply? We may further suppose that his instructor is pointing to the objects as they pass and asking him to name them,—will he not be perplexed? Will he not fancy that the shadows which he formerly saw are truer than the objects that are now shown to him? And if he is brought straight before the light, will he not have a pain in his eyes which will make him turn away from the light and take refuge in the objects which he can see, and which he will consider to be clearer than the realities which are now being shown to him? He will take time to grow accustomed to the sight of the upper world. And finally, he will see the sun himself in his proper place, and not as reflected in another, and he will contemplate him as he is. He will then proceed to argue that this is he who causes the seasons and the years and is the maker of all. that is visible in the world. And when he remembers his old dwelling, the wisdom of the den and his fellow-prisoners, he would greatly felicitate himself on the change that has taken place in him, and pity them for their ignorance. And if he and his companions in the den were in the habit of conferring honours among themselves on those who were clever in observing the fleeting shadows and stating which of them went before, or which followed after, and which were together, and who were therefore best able to draw conclusions in this regard, would he, in his present state of enlightenment, care for such honours and glories, or envy the possessors of them?

This entire allegory may be appended to the previous arguments. The prison-house is the world of the senses, the light of the fire is the sun, the journey upwards is the ascent of the soul to the world of Intelligence, and the sun himself may be compared to the supreme Reality. In this supernal world the Idea of the Good appears as the highest essence, and is known only with an effort. And when known, it is recognised to be the universal author of all things. This is the principle upon which he who would act rationally either in public or private life must have his eye fixed. Plato concludes that those who attain to this beatific vision do not descend again to human affairs, for their souls are ever hastening to the upper world of reality.