This document discusses the importance and purpose of psychology in human life. It begins by defining psychology as the science that studies how people interact with their bio-psycho-socio-cultural environment over time, with the goal of understanding behaviors and internal experiences by identifying the causes behind behaviors at different levels. It then covers the origins of psychology, the etymology of the word, and key figures from the pre-scientific era of psychology. Finally, it discusses how psychology became an independent science in the 19th century with a focus on the scientific study of mental processes and human behavior.