Material nature consists of three modes -- goodness, passion and ignorance. When the eternal living entity comes in contact with nature, O mighty-armed Arjuna, he becomes conditioned by these modes. BG 14.5

O sinless one, the mode of goodness, being purer than the others, is illuminating, and it frees one from all sinful reactions. Those situated in that mode become conditioned by a sense of happiness and knowledge. BG 14.6

The mode of passion is born of unlimited desires and longings, O son of Kunti, and because of this the embodied living entity is bound to material fruitive actions. BG 14.7

O son of Bharata, know that the mode of darkness, born of ignorance, is the delusion of all embodied living entities. The results of this mode are madness, indolence and sleep, which bind the conditioned soul. BG 14.8

All three of these modes keep us conditioned in the bodily concept of life and thus oblige us to remain in the cycle of birth and death repeatedly undergoing the threefold miseries of material existence. The modes are like the waves of the ocean constantly tossing us this way and that in the struggle for material existence. Instead of being endlessly buffeted in these waves the intelligent course of action is to fully surrender ourselves to Lord Krishna and be delivered by His mercy to the transcendental position beyond the modes of material nature.