VII. The seventh and last aspect of the guṇas is that they never return back to bind purusha again, their teleological purpose being fulfilled or realised. It is of course easy to see that, in these last three stages, purusha has nothing to do; but the guṇas of their own nature suffer these backward modifications and return back to their own primal cause and leave the purusha kevalī (for ever solitary). _Vyāsa-bhāshya_, II. 15. Vyāsa says that as the science of medicine has four divisions: (1) disease, (2) the cause of disease, (3) recovery, (4) medicines; so this Yoga philosophy has also four divisions, viz.: (I) Saṃsāra (the evolution of the prakṛti in connection with the purusha). (II) The cause of saṃsāra. (III) Release. (IV) The means of release. Of these the first three have been described at some length above. We now direct our attention to the fourth. We have shown above that the ethical goal, the ideal to be realised, is absolute freedom or kaivalya, and we shall now consider the line of action that must be adopted to attain this goal—the _summum bonum_. All actions which tend towards the approximate realisation of this goal for man are called kuśala, and the man who achieves this goal is called kuśalī. It is in the inherent purpose of prakṛti that man should undergo pains which include all phenomenal experiences of pleasures as well, and ultimately adopt such a course of conduct as to avoid them altogether and finally achieve the true goal, the realisation of which will extinguish all pains for him for ever. The motive therefore which prompts a person towards this ethico-metaphysical goal is the avoidance of pain. An ordinary man feels pain only in actual pain, but a Yogin who is as highly sensitive as the eye-ball, feels pain in pleasure as well, and therefore is determined to avoid all experiences, painful or so-called pleasurable. The extinguishing of all experiences, however, is not the true ethical goal, being only a means to the realisation of kaivalya or the true self and nature of the purusha. But this means represents the highest end of a person, the goal beyond which all his duties cease; for after this comes kaivalya which naturally manifests itself on the necessary retirement of the prakṛti. Purusha has nothing to do in effectuating this state, which comes of itself. The duties of the purusha cease with the thorough extinguishing of all his experiences. This therefore is the means of extinguishing all his pains, which are the highest end of all his duties; but the complete extinguishing of all pains is identical with the extinguishing of all experiences, the states or vṛttis of consciousness, and this again is identical with the rise of prajñā or true discriminative knowledge of the difference in nature of prakṛti and its effects from the purusha—the unchangeable. These three sides are only the three aspects of the same state which immediately precede kaivalya.