Yoga tacitly assumed a certain kind of analysis of the nature of these mental states which sought to find out, if possible, the nature of their constituent elements or moments of existence. Now in analysing the different states of our mind we find that a particular content of thought is illuminated and then passed over. The ideas rise, are illuminated and pass away. Thus they found that “movement” was one of the principal elements that constituted the substance of our thoughts. Thought as such is always moving. This principle of movement, mutation or change, this energy, they called rajas. Now apart from this rajas, thought when seen as divested of its sensuous contents seems to exhibit one universal mould or form of knowledge which assumes the form of all the sensuous contents that are presented to it. It is the one universal of all our particular concepts or ideas—the basis or substratum of all the different shapes imposed upon itself, the pure and simple. Sattva in which there is no particularity is that element of our thought which, resembling purusha most, can attain its reflection within itself and thus makes the unconscious mental states intelligible. All the contents of our thought are but modes and limitations of this universal form and are thus made intelligible. It is the one principle of intelligibility of all our conscious states. Now our intellectual life consists in a series of shining ideas or concepts; concepts after concepts shine forth in the light of the pure intelligence and pass away. But each concept is but a limitation of the pure shining universal of our knowledge which underlies all its changing modes or modifications of concepts or judgments. This is what is called pure knowledge in which there is neither the knower nor the known. This pure object—subjectless knowledge differs from the pure intelligence or purusha only in this that later on it is liable to suffer various modifications, as the ego, the senses, and the infinite percepts and concepts, etc., connected therewith, whereas the pure intelligence remains ever pure and changeless and is never the substratum of any change. At this stage sattva, the intelligence-stuff, is prominent and rajas and tamas are altogether suppressed. It is for this reason that the buddhi or mind is often spoken of as the sattva. Being an absolute preponderance of sattva it has nothing else to manifest, but it is its pure-shining self. Both tamas and rajas being mostly suppressed they cannot in any way affect the effulgent nature of this pure shining of contentless knowledge in which there is neither the knower nor the known. But it must be remembered that it is holding suspended as it were within itself the elements of rajas and tamas which cannot manifest themselves owing to the preponderance of the sattva.