The word Psychology comes from a combination of Greek words psyche which means life or soul and logia meaning reason. Today psychology is known for the study of human mind and its functions. Psychology is the science that studies behaviour and mental processes of individuals or group of people. They study all kinds of behaviour not only abnormal behaviour. They try to explain, predict, describe and control behaviour. The history of psychology can be traced ancient philosophers and their philosophies. The Greeks have been known to be the promoters of the natural sciences and philosophy. They gave us basic philosophies, starting with metaphysics. “Metaphysics is a part philosophy that asks questions such as, what is the world made of?” (p13). The second one is epistemology, it is the philosophy of knowledge. Lastly, the third aspect of philosophy is ethics, it is the philosophical understanding of good-bad and right-wrong. The two main philosophical influences on the modern development of psychology are Empiricism and Rationalism. Empiricism “says that all knowledge comes through the sense” (p16). And rationalism “which says that knowledge is a matter of reason, thought” (p16). These two ideas promote the development of psychology as a science. Therefore, it can be said that philosophy and psychology correlate with each other while having the same ideas. Aristotle adopted a philosophical approach to defining the structure of mind and behaviour, his theory was influenced by Plato. Democritus introduced the idea that human identify qualities by convention. Like we call comedy movies comedy, this how we group things together. This process is called “nominalism”, the Latin word for a name. According to Democritus soul or mind is made up of small and soft atoms, which can be found in humans and animals. His theory was based on integrity and happiness. In conclusion, psychology is a study of human mind. There is endless number of things to study. Each day new things are discovered about the human mind and there are some things yet to be discovered. It has the power to change the world. Psychology will continue to improve and will have great influence on everyone.