Greek philosophers Plato (left) and Aristotle, as depicted in a detail of the 1509 fresco The School of Athens. Both had a major influence on early concepts of the human mind.

      Does life have a purpose?

      Aristotle believed that everything on Earth has a purpose, a telos. The acorn is intended to grow into an oak, a knife is intended to cut, a baker is intended to bake. As human beings are the only animals that reason, it is our telos to reason; it is our purpose. If we live according to our purpose, we will be living virtuously and will consequently be happy.

      There are two types of telos: intrinsic telos and extrinsic telos. Intrinsic telos suggests that the aim of the organism is inherent in its nature, an acorn is innately programmed to grow into a tree. Extrinsic telos refers to a purpose imposed by an external force, such as a deity.

      Not all modern views hold that life has a purpose, however. In the Darwinian view of natural selection, genetic variations happen by chance and persist only if they turn out to be adaptive, if they promote the survival of the species. We reason not because it is our telos but because we happen to have evolved that way. Our capacity to reason helped our species to survive.

      The teleological view is more consistent with other modern views, though. Abraham Maslow (1908–1970), a humanistic psychologist, believed that we are predisposed to strive for a state of self-actualization, in which our personality is fully flowered and we reach our full emotional potential. It is, in effect, our telos.

      Sigmund Freud (1856-1939), as well, may have been influenced by teleology. He studied with Franz Brentano (1938-1917), who was a scholar of Aristotle.

      Did Plato’s ideas anticipate Freud in any way?

      Plato also had ideas about emotions and emotional control that anticipated Freud’s theories of the ego and the id. Plato’s three-part division of the soul into appetite, reason, and temper (also known as the spirited part of the soul) has been linked to Freud’s division of the mind into the id, ego, and superego. Plato also believed in controlling the bodily passions in order to turn one’s desire toward loftier goals, as described in his metaphor of the soul as a charioteer with a pair of winged steeds. One steed is immortal like the steeds of the gods and aspires toward contemplation of spiritual beauty. The other steed is mortal and plunges toward earth and toward animalistic passions and desire. The chariot must rein in the steed of animal appetites in order for the soul to gain true happiness. We can link the earthly steed to the id and the charioteer to the ego. More loosely, we could tie the immortal steed to the superego.

      Did the Roman statesman Cicero have anything to add about the mind?

      The Romans were better known for their practical accomplishments in the fields of law, engineering, and warfare than for their philosophical works but some contributions are worth noting. Cicero (106–42 B.C.E.), the famous Roman orator, gave a detailed description of the passions. He grouped the passions into four categories: discomfort, fear, pleasure or joy, and desire (libido in Latin). We can wonder whether Freud’s use of the term libido was influenced by Cicero.

      How does the belief in demonic possession relate to psychology?

      The idea of the devil was pervasive throughout the Middle Ages and pre-scientific Europe, and all manner of illness and misfortune was attributed to Satan or lesser devils and demons. Mental illness, in particular, was seen to be caused by demonic possession. It was believed that Jesus exorcised demons, a task that was performed by priests in the Middle Ages. Even today some people believe in demonic possession.

      What happened to the Greeks’ ideas after the fall of the Roman Empire?

      The ideas of the Greek philosophers spread throughout the Roman Empire and remained influential until its fall in the fourth century C.E. By then Christianity was the official religion of the Roman Empire, and following the fall of Rome, the Christian church was essentially its sole surviving institution. Although many aspects of pagan philosophical thought were integrated into church teaching (e.g., Plato’s idea of the immortal soul), anything that did not fit with Christian theology was considered heretical. In Christendom, meaning most of Europe, this state of affairs remained largely unchanged until the dawn of the modern era. Thus questions of psychology were addressed through medieval Christianity.

      How were questions of psychology addressed in medieval Christianity?

      In general, medieval Christianity focused more on the next world than on our happiness within this one. True happiness would only be found in Heaven, not on earth, and entrance to Heaven could only be found through religious piety. Free will was emphasized by St. Augustine (354–430 C.E.), the most influential Christian theologian in the first millennium C.E. Every individual has the free will to choose whether or not to follow God. Sex and the passions of the body were considered sinful, unless performed within a marriage for the purpose of childbearing. Belief in the devil was also widespread and mental illness was often seen as a manifestation of possession by the devil

      What was happening in the Muslim world during the Middle Ages?

      Within one century after the death of the Islamic prophet Mohammed (570–632), Muslim armies had conquered almost all of the southern and eastern Mediterranean, encompassing essentially the southern half of the former Roman Empire. In contrast to northern Europe where the advanced culture of the Greco-Roman world was largely lost for a millennium, the literature of the ancient scholars was preserved in medieval Islam and several centers of learning were established across the Arab world. Avicenna (980–1031), who was known in Arabic as Ibn Sina, was committed to the synthesis of classical literature with Islamic doctrine.

      Despite a traumatically peripatetic life, Avicenna succeeded in writing one of the most influential texts in the history of medicine, known as the Canon of Medicine. As a physician, he was very familiar with psychological illness. He endorsed the doctrine of the four humors in the tradition of Hippocrates and Galen as well as the brain’s role in psychological disturbances. His theory about inner senses addressed the relationships between perception, memory, and imagination. He even speculated about what parts of the brain control different psychological functions.

      When did more modern approaches to psychology begin?

      After the European Renaissance (fifteenth to sixteenth centuries) brought a sea change of cultural and intellectual values, attention was drawn away from the world beyond and back to this world. There was a renewed interest in and awareness of ancient Greek and Roman thought and its focus on the natural world. This new orientation was known as humanism and led to revolutions in philosophical thought. Many important philosophers from the early modern era addressed questions of the mind in ways that still have relevance to modern psychology. The Renaissance also heralded the beginnings of modern science.

      Who were some influential philosophers in early modern times and what did they have to say about the mind?

      From the Renaissance on, philosophers started to revisit the questions asked by the ancient Greeks and then built upon those ideas to create a new way of seeing the mind. While psychology per se did not exist yet, philosophy was beginning to lay the groundwork for what would later become psychology. Philosophers of note included René Descartes (1596–1650), Benedict de Spinoza (1632–1677), Thomas Hobbes (1588–1679), and John Locke (1632–1704).