This book explores the profound, yet often overlooked, role of color in healthcare and bioethics, arguing that color is far more than a visual or aesthetic element—it actively shapes human experience, perception, and ethical reasoning. Traditionally regarded as secondary to objective medical observations or rational ethical debates, color has been marginalized in these fields, considered subjective and inconsequential. However, this book reveals that color is critical in diagnostic and therapeutic practices and that it subconsciously influences moral interpretations in bioethics. Through examples like the ‘blue hour’—a time of day associated with melancholy and creativity—readers are invited to consider color not just as a physical phenomenon explained by wavelengths and visual physiology, but as a medium rich with emotional and metaphorical meaning. From ‘feeling blue’ to seeing the world in ‘black and white’, color conveys complex messages that inform our perceptions of health, morality, and identity. By bridging the gap between science, emotion, and ethics, this book illuminates how colors impact our worldviews, urging readers to consider the subtle yet significant ways that color influences our understanding of ourselves and the world around us.