Berkeley pushes forward the arguments of Locke and asks: if our knowledge is confined to sensations and reflective operations or ideas, how can we know that there is a real and independent world outside? When our consciousness is the only thing that we directly know, it becomes impossible for us to know the existence of an outside world. Further, the existence of a spatial and material world would, he thinks, deny the existence of God, for it would limit Him and thus cancel His validity. Berkeley seeks to refute atheism and irreligion by denying the existence of the world of matter.
The existence of a thing, according to Berkeley, consists in its being perceived. Our thoughts and ideas, again, have their existence in their being perceived. Our sensations, too, have their existence in their being perceived. By "being perceived" he means, of course, "to be experienced in some way or the other". How can we know that these exist when they are not perceived or contained in our consciousness? An object, I say, exists, because I perceive it, feel it. Even the primary qualities of Locke are as unintelligible as the secondary qualities. We have no way of knowing if anything exists at all other than these qualities. To assert the existence of a thing when no minds perceive it is, to Berkeley, unwarranted. Hence the objects which are said to exist outside are really perceptions in the mind.
In the Vedanta, creation by the mind has three phases. There is a secondary creation or rather imagination, which can be attributed to individual minds. These individual minds cannot affect the realities of things as such. When a perceiving individual comes in relation to an external object, what happens is that the external object greatly influences the mental condition of the individual, and the individual, in turn, perceives in the object those characteristics which lie latent in its mind. In essence, the individual's mental constitution gets unconsciously objectified in the perception of an object. Nothing can be perceived as it is, but everything is perceived as modified by the relations which the mind of the perceiving individual bears to it. This projection of the inward constitution towards the external object is called Jiva-srishti. The objects themselves, in their independent capacity, belong to the creation of the Cosmic Mind which is independent of and is superior to the individual mind. This latter process of the manifestation of objects may be called primary creation or Ishvara-srishti. The latter process of creation has universal validity and reality. There is also a third way in which objects get influenced by mental phenomena; and that is the condition of objects when they are conceived of as being acted on by the collective totality of the individual minds existing in the universe.
It does not, however, mean that there is nothing outside our individual perceptions or ideas. Every externalised perception should have a basis or support. There cannot be even an appearance without a substratum or reality. The basis of our perceptions or sensations is a material world outside, which, again, has its support or reality in God, the Supreme Spirit. Berkeley would say that the idea of a support is itself an imaginary abstraction. But, to the Vedanta, the idea of a support does not arise through any such abstraction, for it is the necessary implication of the irrefutable existence of our individual beings. The Vedanta, however, would accept Berkeley's position that the world is not extra-mental in the sense that it is a perception of the totality of minds or of the Mind of God. That other minds also perceive the same objects as I perceive proves not the independent existence of the objects, but that all minds are limited to a similar constitution. A different constitution of minds would make them perceive the world in quite a different manner, with laws governing it different from the present ones.
The relation between dream-experience and waking experience would give us a solution to the problem of the relation between individual perception and universal perception. It will be observed that the subject of dream-experience is differentiated by a knowledge-relation from the objects constituting the world of dream-experience. In the waking state too we find that the individual perceiver is differentiated by a knowledge-relation from the external objects which form the contents of the world of waking-experience. But the subject in dream as well as all its objects together with the space and time of dream are included and transcended in the mental constitution of the waking individual. We will be able to account for our experiences in this world only by explaining the presence of the waking subject and all the objects of the waking experience in the Universal Mind which we call God. Berkeley, too, says later as a modification of his previous doctrine, that the objects, if they are not contained in my mind, may be in the mind of some other spirit, or in the Mind of God, thus proving that matter cannot ultimately have an extra-mental reality, though it may not be contained in any individual mind.
Berkeley establishes the existence of an eternal Spirit, which is the cause of our sensations, by the observation of the fact that our sensations are not voluntary actions; they occur independently of our willing them to be or not to be. Moreover, our sensations are stronger than our imaginations, for they present a greater reality with greater steadiness and order. Berkeley here approaches the distinction made in the Vedanta between Jiva-srishti and Ishvara-srishti when he says that our imaginations are less real, being only images of things represented or copied, while the ideas of sensations received from the eternal Spirit are real things. In the latter modified aspect of his theory, Berkeley comes nearer to the Advaita-Vedanta, for which the universe has a relative reality, more real than the imaginations of the individuals, and the universe is a manifestation of God Himself. Materiality and mechanism are not in God, but His form as the universe appears to be so endowed on account of its being made a sense-object in the realm of space-time.
Berkeley thinks that by the refutation of the existence of an extra-mental matter and reducing it to mere ideas, he has also refuted idolatry, for people will not worship their own ideas. It was already said that in the Vedanta matter is not an idea in any particular individual mind, but is outside it, though it loses its materiality when it becomes the content of the Cosmic Mind. Idols and images of worship cannot become mere ideas in the minds of people, for they are outside their minds, though within the Cosmic Mind. Matter is not non-existent to the individuals. The use of idols in worship has an inner meaning and significance. The worshipper does not usually confine his idea of God to the particular idol that he worships, but he makes it a representation or a symbol of the presence of God, Who is infinite and immaterial. The mind finds it hard to contemplate on the super-sensuous Infinite Spirit and so we take idols as aids in the concentration of mind in the process of spiritual meditations. What becomes the object of contemplation is not the material of which the idol is made, but the supreme attributes of God which are superimposed on it. Even supposing that the worshipper of an idol limits his conception of God to the form of the idol, the worship in no way loses its value. By constant meditation on the idol as the form of God the mind begins to see it everywhere and loses consciousness of the other objects of the world. The meditator reaches a stage where he is taken beyond the idea of the idol and gets absorbed in the divine consciousness, which is the supreme goal of meditation. Those who level diatribes against worship of idols do not thoroughly grasp the psychology of such worship and the metaphysics behind it.