When the government forgets its duty to propagate the spiritual knowledge and devotion, the responsibility falls finally on the underlying ultimate government of which the Lord is the head. Therefore, the Lord comes down in human form to propagate this spiritual knowledge and devotion. The Lord also collects some tax from you for His mission. He has already given some facilities to you, like human birth, longevity, health, wealth etc. The human government collects taxes without caring for your problems. But the Lord asks for tax from all of you, but this tax is only the time, energy or work and money, which you waste in illusory entertainments. You can do the sacrifice of your work (Karma Sanyasa) or the sacrifice of the fruit of work (Karmaphala Tyaga) or both according to your convenience. The liberated souls sacrifice fully, which is impossible for all others and such liberated souls are blessed by the Lord to be His constant associates, which is the permanent result. The former case is Pravritti [partial sacrifice] and the latter case is Nivritti [complete sacrifice]. One should keep Nivritti as the ultimate aim.