परित्राणाय साधूनां विनाशाय च दुष्कृताम्।
धर्मसंस्थापनार्थाय संभवामि युगे युगे।।4.8।।
।।4.8।। साधु पुरुषों के रक्षण दुष्कृत्य करने वालों के नाश तथा धर्म संस्थापना के लिये मैं प्रत्येक युग में प्रगट होता हूँ।।
Actually there is no mandate that for the protection of the righteous and virtuous Lord Krishna must descend and save them. But by His causeless mercy and in some circumstances for sport He manifests Himself by His own sweet will. In the Rig Veda it is described that this will itself is as an inclination of the Lord. A comparison in human terms it is like the bliss that comes with spontaneous creativity. The Supreme Lord is complete within Himself so there is nothing to be gained for Him by any action; yet and still He still performs unlimited activities. Therefore those expert in bhagavat tattva or knowledge of the Supreme Lord Krishna declare that His impulses are all sublime and transcendental to prakriti or material nature. The word glanir in the previous verse does not mean decline as is often translated but glanir means obscure. If dharma meaning eternal righteous is a perennial principle then it must be devoid of any modification of decline. It has to exist eternally in pristine purity. What happens is that dharma becomes obscure to the masses due to material influences on the mind, agitated by the effects of sense gratification by the onslaught of maya or illusion. When such times arise the purpose of human existence becomes distorted and consequently the activities of humans become more and more degenerated and humans become degraded. At this time the dharma of human beings is said to be glanir or obscured. Therefore as far as dharma is concerned there is no possibility of their being any decline even as darkness is unable to hide sunlight. However even as large clouds are able to obscure the light of the sun from human vision in the same way non-awareness of the independent supremacy of the Supreme Lord and the human beings total dependency on the Supreme Lord consequently obscures the faith in the Supreme Lord as well as any perception of the Supreme Lord in human beings. So the sense is that glanir is referring to obscurity. The Supreme Lord Krishna is also designated as Brahman which means eternal in time and dynamic in creativity and is the all pervading luminosity of His effulgence. It is not inert or passive. The word Brahman which is derived from the root brh means to grow, to burst forth which infers constant, continuous creativity, perpetually manifesting. That which is dynamic and creative cannot remain static and passive. The dynamic, spontaneous, creative impulse is what is known as the Supreme Lord Krishnas lila or divine pastimes. The complete material creation and all its embodied beings is the result of one such impulse of the Supreme Lord Krishna and this is also known as lila. The reality of Lord Krishnas avatars or incarnations such as Rama or Buddha and the understanding of Lord Krishnas divine lilas has often been misconstrued and misinterpreted. But here in this verse He explicitly reveals that he comes to protect the righteous and to vanquish the sinful miscreants and to personally re-establish dharma or eternal righteousness. Sam-sthapana-arthaya- ca infers to establishing ones true nature. The Lords divine nature assumes His divine form. Because prakriti or material nature is understood as svabhava the word sam has been used referring to that. The word sva also refers Lord Krishnas essential svarupa or transcendental form as svabhava refers to the innate form or essence and creation is manifested by this essence being the impulse of His will. There is no difference between the form of Krishna and Himself neither is there any difference between the name of Krishna and Himself. In the Narayana Sruti is states that : the Supreme Lord Krishna is immutable yet through the course of creation He manifests Himself in inconceivable many ways in unlimited forms.