The universe is created to gradually rectify the contaminated souls trying to exploit material nature. The Lord moves the conditioned souls along, according to their karma, through the various stages of spiritual rectification. Thus the Lord is like a herdsman (the word paśu-pāla literally means “protector of animals”), who moves the creatures under his protection to various pastures and watering spots in order to protect them and sustain them. A further analogy is that of a doctor, who moves the patient under his care to various areas of a hospital for diverse kinds of examination and treatment. Similarly, the Lord brings us through the network of material existence in a gradual cleansing process so that we can enjoy our eternal life of bliss and knowledge as His enlightened associates.
Source:A.C. Bhaktivedanta Swami Prabhupada (2014 edition), “Srimad Bhagavatam”, Tenth Canto, Chapter 51 – Text 19