Now these guṇas take three different courses of development from the ego or ahaṃkāra according to which the ego or ahaṃkāra may be said to be sāttvika, rājasa and tāmasa. Thus from the sāttvika side of the ego by a preponderance of sattva the five knowledge-giving senses, e.g. hearing, sight, touch, taste and smell are derived. From the rajas side of ego by a preponderance of rajas the five active senses of speech, etc., are derived. From the tamas side of ego or ahaṃkāra by a preponderance of tamas are derived the five tanmātras. From which again by a preponderance of tamas the atoms of the five gross elements—earth, water, fire, air and ether are derived. In the derivation of these it must be remembered that all the three guṇas are conjointly responsible. In the derivation of a particular product one of the guṇas may indeed be predominant, and thus may bestow the prominent characteristic of that product, but the other two guṇas are also present there and perform their functions equally well. Their opposition does not withhold the progress of evolution but rather helps it. All the three combine together in varying degrees of mutual preponderance and thus together help the process of evolution to produce a single product. Thus we see that though the guṇas are three, they combine to produce on the side of perception, the senses, such as those of hearing, sight, etc.; and on the side of the knowable, the individual tanmātras of gandha, rasa, rūpa, sparśa and śabda. The guṇas composing each tanmātra again harmoniously combine with each other with a preponderance of tamas to produce the atoms of each gross element. Thus in each combination one class of guṇas remains prominent, while the others remain dependent upon it but help it indirectly in the evolution of that particular product. CHAPTER IV THE PROCESS OF EVOLUTION The evolution which we have spoken of above may be characterised in two ways: (1) That arising from modifications or products of some other cause which are themselves capable of originating other products like themselves; (2) That arising from causes which, though themselves derived, yet cannot themselves be the cause of the origination of other existences like themselves. The former may be said to be slightly specialised (_aviśesha_) and the latter thoroughly specialised (_viśesha_).