Albert Ellis (1913 – 2007) was an American psychologist and psychotherapist who founded Rational Emotive Behavior Therapy (REBT). He held MA and PhD degrees in clinical psychology from Columbia University, and was certified by the American Board of Professional Psychology (ABPP). He also founded, and was the President of, the New York City-based Albert Ellis Institute. He is generally considered to be one of the originators of the cognitive revolutionary paradigm shift in psychotherapy and an early proponent and developer of cognitive-behavioral therapies.

Based on a 1982 professional survey of US and Canadian psychologists, he was considered the second most influential psychotherapist in history (Carl Rogers ranked first in the survey; Sigmund Freud was ranked third). Psychology Today noted that, “No individual—not even Freud himself—has had a greater impact on modern psychotherapy.”

Aaron Beck (1921-2021) is an American psychiatrist who is professor emeritus in the department of psychiatry at the University of Pennsylvania. He is regarded as the father of cognitive therapy and cognitive behavioral therapy. His pioneering methods are widely used in the treatment of clinical depression and various anxiety disorders.

Beck is noted for his writings on psychotherapy, psychopathology, suicide, and psychometrics. He has published more than 600 professional journal articles and authored or co-authored 25 books. He has been named one of the “Americans in history who shaped the face of American psychiatry”, and one of the “five most influential psychotherapists of all time” by The American Psychologist in July 1989.

Alfred Adler (1870 – 1937) was an Austrian medical doctor, psychotherapist, and founder of the school of individual psychology. His emphasis on the importance of feelings of inferiority, the inferiority complex, is recognized as an isolating element that plays a key role in personality development. Alfred Adler considered a human being as an individual whole, and therefore he called his psychology “Individual Psychology” (Orgler 1976).

Adler was the first to emphasize the importance of the social element in the re-adjustment process of the individual and to carry psychiatry into the community.

Carl Gustav Jung (1875 – 1961), was a Swiss psychiatrist and psychoanalyst who founded analytical psychology. Jung’s work has been influential in the fields of psychiatry, anthropology, archaeology, literature, philosophy, psychology, and religious studies. Freud and Jung conducted a lengthy correspondence and collaborated, for a while, on a joint vision of human psychology.

Jung’s research and personal vision, however, made it impossible for him to follow his older colleague’s doctrine and a schism became inevitable.

Among the central concepts of analytical psychology is individuation—the lifelong psychological process of differentiation of the self out of each individual’s conscious and unconscious elements.

Viktor Emil Frankl (1905 –  1997) was an Austrian neurologist, psychiatrist, philosopher, author, and Holocaust survivor.

He was the founder of logotherapy, a school of psychotherapy that describes a search for life meaning as the central human motivational force. Logotherapy is part of existential and humanistic psychology theories.

Logotherapy was recognized as the third school of Viennese Psychotherapy; the first school was created by Sigmund Freud, and the second by Alfred Adler.

Daniel Kahneman (1934 – alive) is a psychologist and economist notable for his work on the psychology of judgment and decision-making, as well as behavioral economics, for which he was awarded the 2002 Nobel Memorial Prize in Economic Sciences (shared with Vernon L. Smith). His empirical findings challenge the assumption of human rationality prevailing in modern economic theory.

In 2011, he was named by Foreign Policy magazine in its list of top global thinkers. In the same year, his book Thinking, Fast and Slow, which summarizes much of his research, was published and became a best seller. In 2015, The Economist listed him as the seventh most influential economist in the world.

He is professor emeritus of psychology and public affairs at Princeton University’s Princeton School of Public and International Affairs.

Jiddu Krishnamurti (1895 – 1986) was a philosopher, speaker, and writer. In his early life, he was groomed to be the new World Teacher, but later rejected this mantle and withdrew from the Theosophy organization behind it. His interests included psychological revolution, the nature of mind, meditation, inquiry, human relationships, and bringing about a radical change in society. He stressed the need for a revolution in the psyche of every human being and emphasized that such a revolution cannot be brought about by any external entity.

Krishnamurti wrote many books, among them The First and Last Freedom, The Only Revolution, and Krishnamurti’s Notebook. Many of his talks and discussions have been published.

Alan Wilson Watts (1915 – 1973) was an English writer, philosopher, theologian, and speaker known for interpreting and popularizing Buddhism, Taoism, and Hinduism for a Western audience. 

He wrote more than 25 books and articles on religion and philosophy. Alan Watts was one of the first to interpret Eastern wisdom for a Western audience.

“Perhaps the foremost interpreter of Eastern disciplines for the contemporary West, Alan Watts had the rare gift of ‘writing beautifully the un-writable’. Watts begins with scholarship and intellect and proceeds with art and eloquence to the frontiers of the spirit. A fascinating entry into the deepest ways of knowing.” — LA Times

Ramana Maharshi (1879 – 1950) is mostly known by the name Bhagavan Sri Ramana Maharshi.

In later years, visitors received instruction by sitting silently in his company asking questions. Since the 1930s his teachings have been popularized in the West.

Ramana Maharshi approved a number of paths and practices but recommended self-inquiry as the principal means to remove ignorance and abide in Self-awareness, together with surrender to the Self.

He is most well known for his ‘who am I?’ method of self-inquiry in order to abide in the true self.

Moses ben Maimon (1138–1204), commonly known as Maimonides, was a medieval philosopher who became one of the most prolific and influential scholars of the Middle Ages. In his time, he was also a preeminent astronomer and physician, serving as the personal physician of Saladin.

Aside from being revered by Jewish historians, Maimonides also figures very prominently in the history of Islamic and Arab sciences and is mentioned extensively in studies. Influenced by Al-Farabi, Ibn Sina, and his contemporary Ibn Rushd, he became a prominent philosopher and polymath in both the Jewish and Islamic worlds. The famous Christian philosopher, Saint Thomas Aquinas (1225–74) was also proficient in Maimonides’ philosophical writings and quotes him. On his tomb is inscribed “From Moses to Moses there was none like Moses”.

Epictetus (50 – 135 AD) was a Greek Stoic philosopher – a philosophy of personal ethics informed by its system of logic and its views on the natural world. According to its teachings, as social beings, the path to eudaimonia (happiness) is found in accepting the moment as it presents itself, by not allowing oneself to be controlled by the desire for pleasure or by the fear of pain, by using one’s mind to understand the world and to do one’s part in nature’s plan, and by working together and treating others fairly and justly. His teachings were written down and published by his pupil Arrian in his books, Discourses, and Enchiridion.

Epictetus taught that philosophy is a way of life and not just a theoretical discipline. To Epictetus, all external events are beyond our control; we should accept whatever happens calmly and dispassionately. However, individuals are responsible for their own actions, which they can examine and control through rigorous self-discipline.

Marcus Aurelius Antoninus (121 – 180 AD) was a Roman emperor from 161 to 180 and a Stoic philosopher. He was the last of the rulers known as the Five Good Emperors. An age of relative peace and stability for the Roman Empire.

The Column and Equestrian Statue of Marcus Aurelius still stand in Rome, where they were erected in celebration of his military victories. Meditations, the writings of “the philosopher” – as contemporary biographers called Marcus, are a significant source of the modern understanding of ancient Stoic philosophy. They have been praised by fellow writers, philosophers, monarchs and politicians centuries after his death.