The Three Gunas
Sattva, rajas, and tamas—these three qualities born of nature bind the immortal soul to the body.
The three gunas (qualities of nature) are the fundamental forces that compose material existence. Sattva brings purity, light, and goodness; rajas brings passion, activity, and restlessness; tamas brings darkness, inertia, and ignorance. Every aspect of the manifest world, including our minds and bodies, is a mixture of these three. Understanding the gunas helps us navigate life and progress spiritually by cultivating sattva while transcending all three.
Material nature consists of the three modes—goodness, passion, and ignorance. When the living entity comes in contact with nature, he becomes conditioned by these modes.
The guna theory provides a remarkably sophisticated psychology, explaining variations in temperament, mood, and behavior through shifting proportions of these forces.
Bhagavad Gita