René Descartes (1596–1650), often hailed as the father of modern philosophy, made a profound contribution to the development of psychology through his concept of mind-body dualism. In an era dominated by religious and metaphysical explanations of human experience, Descartes boldly proposed that the mind and body are two fundamentally distinct substances: the mind as a non-material, thinking entity (res cogitans), and the body as a material, mechanical one (res extensa). This idea, articulated most clearly in his 1641 work Meditations on First Philosophy, laid the foundation for the scientific study of mental processes as separate from purely biological functions. Though later thinkers would challenge and refine his dualism, Descartes’ vision helped carve out space for psychology as an independent field, one concerned not only with the brain, but with consciousness, thought, and the inner workings of the human soul. His legacy endures as a spark that helped ignite the modern exploration of mind and behaviour. His example encourages us to pursue the truth rather than accept false dogmas, whether they be scientific or religious. The Christian scientist who daily walks and talks with God will make discoveries that wholly agree with Divine revelation.