Half Empty, Half Full is a thought-provoking collection of essays that explores the intersections between psychology, neuroscience, philosophy, and culture through a poetic and critical lens. Written over more than a decade, Luiz H. Santana's book invites readers into a reflective journey through the history, theory, and practice of psychological science, while challenging traditional boundaries between empirical inquiry and existential contemplation. Drawing from fields as diverse as behavioral neuroscience, evolutionary psychology, aesthetics, epistemology, and science fiction, each essay blends scholarly insight with narrative grace. Half Empty, Half Full is an invitation to rethink the nature of behavior, the ethics of science, and the limits of knowledge itself in an era of digital transformation and ecological urgency. It is a book for psychologists, educators, scientists, and curious minds who believe that thinking about science can—and must—also be a humanistic act.