In spirituality, "density" refers to a soul's level of consciousness or vibrational frequency. The lower the density, the more contracted, heavy, and physical the experience (e.g., ego and survival). The higher the density, the more expanded, light, and connected the consciousness is to universal truth .1st Density: Physical existence and awareness (associated with organic matter, rocks, and water).2nd Density: Growth and feeling (the consciousness of plants and animals).3rd Density: Self-awareness, ego, and free will (human experience). It is characterized by the choice between service-to-self or service-to-others.4th Density: Love, understanding, and compassion (a state of being characterized by unity and deep empathy).5th Density: Wisdom and light (a focus on truth and spiritual exploration).6th Density: The blending of love and wisdom (a state of recognizing the underlying connectedness of all things).7th Density: The gateway to unity (source consciousness).Alternatively, Christian mystics and theologians (such as C.S. Lewis in The Great Divorce) use the term "ontic density" to describe the "thickness" or substance of spiritual reality. In this context, God and the spiritual realm are viewed as infinitely denser and more substantial than the physical, temporary world.