In Elie Wiesel's book "Day," the profound observation about human existence emphasizes the impact of one's physical position on their perception of life. The distinction between being horizontal and vertical symbolizes different states of awareness and experience. When a person is horizontal, they may feel vulnerability or introspection, whereas a vertical position often represents active engagement and presence. This duality highlights how perspective shifts depending on one's situation.

The quote also reflects on the nuanced way shadows can alter our perception of others and ourselves. Shadows cast on walls and faces can indicate feelings, moods, or states of being, suggesting that how we view our surroundings can change based on our physical and emotional positions. Wiesel’s exploration of these themes captures the complex relationship between the body and the mind in the journey of human life.