Now though the modifications of the ego are formed successively by the preponderance of sattva, rajas and tamas, yet the rajas is always the accessory cause (_sahakāri_) of all these varied collocations of the guṇas; it is the supreme principle of energy and supplies even intelligence with the energy which it requires for its own conscious activity. Thus Lokācāryya says in his _Tattvatraya_: “the tāmasa ego developing into the material world and the sāttvika ego developing into the eleven senses, both require the help of the rājasa ego for the production of this development” (_anyābhyāṃ ahaṃkārābhyām svakāryyopajanane rājasāhaṃkūraḥ sahakārī bhavati_); and Barabara in his _Bhāshya_ writes: “just as a seed-sprout requires for its growth the help of water as instrumental cause, so the rājasa ahaṃkāra (ego) works as the accessory cause (_sahakāri_) for the transformations of sāttvika and tāmasa ahaṃkāra into their evolutionary products.” The mode of working of this instrumental cause is described as “rajas is the mover.” The rājasa ego thus moves the sattva part to generate the senses; the tamas part generating the gross and subtle matter is also moved by the rajas, agent of movement. The rājasa ego is thus called the common cause of the movement of the sāttvika and the tāmasa ego. Vācaspati also says: “though rajas has no separate work by itself yet since sattva and tamas (which though capable of undergoing modification, do not do their work) are actionless in themselves, the agency of rajas lies in this that it moves them both for the production of the effect.”[27] And according as the modifications are sāttvika, tāmasa or rājasika, the ego which is the cause of these different modifications is also called vaikārika, bhūtādi and taijasa. The mahat also as the source of the vaikārika, taijasa and bhūtādi ego may be said to have three aspects. Now speaking of the relation of the sense faculties with the sense organs, we see that the latter, which are made up of the grosser elements are the vehicle of the former, for if the latter are injured in any way, the former are also necessarily affected.[28] To take for example the specific case of the faculty of hearing and its organ, we see that the faculty of hearing is seated in the ether (_ākāśa_) within our ear-hole. It is here that the power of hearing is located. When soundness or defect is noticed therein, soundness or defect is noticed in the power of hearing also. When the sounds of solids, etc., are heard, then the power of hearing located in the hollow of the ear stands in need of the resonance produced in the ākāśa of the ear.