Krsna does not change His constitutional position, not even when He appears in this material world. Ordinary living entities have their constitutional spiritual positions covered. They appear in different bodies, and under the different bodily concepts of life they act. But Krsna does not change His body. He appears in His own body and is therefore not affected by the modes of material nature. In the First Canto, 11th Chapter, 24th verse, of Srimad-Bhagavatam it is stated that the special prerogative of the supreme controller is that He is not at all affected by the modes of nature. The practical example of this is that devotees who are under the protection of the Lord are also not affected by material nature. To overcome the influence of material nature is very difficult, but the devotees or the saintly persons who are under the protection of the Lord are not affected. So what need is there to speak of the Lord Himself? To be more clear, although the Lord sometimes appears in this material world, He has nothing to do with the modes of material nature, and He acts with full independence in His transcendental position. This is the special quality of the Lord.