Idealism holds that the most basic unit of reality is conceptual rather than material. There are several types of idealism: subjective idealism views reality as constituted by consciousness and its contents; divine idealism sees reality as manifestations of God's mind; ontological idealism argues reality is made of ideas or concepts at its foundation; and epistemological idealism focuses on how the mind structures our understanding of reality. Idealism contrasts with materialism, which views the physical world as the only true reality and consciousness as a physical process in the brain.