Aristotle

Epicurus was an ancient Greek philosopher as well as the founder of the school of philosophy called Epicureanism. Only a few fragments and letters remain of Epicurus's 300 written works. Much of what is known about Epicurean philosophy derives from later followers and commentators. For Epicurus,... the purpose of philosophy was to attain the happy, tranquil life, characterized by ataraxia—peace and freedom from fear—and aponia—the absence of pain—and by living a self-sufficient life surrounded by friends. He taught that pleasure and pain are the measures of what is good and evil, that death is the end of the body and the soul and should therefore not be feared, that the gods do not reward or punish humans, that the universe is infinite and eternal, and that events in the world are ultimately based on the motions and interactions of atoms moving in empty space. His parents, Neocles and Chaerestrate, both Athenian-born, and his father a citizen, had emigrated to the Athenian settlement on the Aegean island of Samos about ten years before Epicurus's birth in February 341 BCE.
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Plato was a Classical Greek philosopher, mathematician, student of Socrates, writer of philosophical dialogues, and founder of the Academy in Athens, the first institution of higher learning in the Western world. Along with his mentor, Socrates, and his student, Aristotle, Plato helped to lay the... foundations of Western philosophy and science. In the words of A. N. Whitehead: The safest general characterization of the European philosophical tradition is that it consists of a series of footnotes to Plato. I do not mean the systematic scheme of thought which scholars have doubtfully extracted from his writings. I allude to the wealth of general ideas scattered through them. Plato's sophistication as a writer is evident in his Socratic dialogues; thirty-six dialogues and thirteen letters have been ascribed to him. Plato's writings have been published in several fashions; this has led to several conventions regarding the naming and referencing of Plato's texts. Plato's dialogues have been used to teach a range of subjects, including philosophy, logic, ethics, rhetoric, and mathematics.
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Hippocrates of Cos or Hippokrates of Kos was an ancient Greek physician of the Age of Pericles , and is considered one of the most outstanding figures in the history of medicine. He is referred to as the father of Western medicine in recognition of his lasting contributions to the field as the... founder of the Hippocratic School of Medicine. This intellectual school revolutionized medicine in ancient Greece, establishing it as a discipline distinct from other fields that it had traditionally been associated with , thus establishing medicine as a profession. However, the achievements of the writers of the Corpus, the practitioners of Hippocratic medicine, and the actions of Hippocrates himself are often commingled; thus very little is known about what Hippocrates actually thought, wrote, and did. Hippocrates is commonly portrayed as the paragon of the ancient physician, credited with coining the Hippocratic Oath, still relevant and in use today.
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Heraclitus of Ephesus was a pre-Socratic Greek philosopher, a native of the Greek city Ephesus, Ionia, on the coast of Asia Minor. He was of distinguished parentage. Little is known about his early life and education, but he regarded himself as self-taught and a pioneer of wisdom. From the lonely... life he led, and still more from the riddling nature of his philosophy and his contempt for humankind in general, he was called "The Obscure" and the "Weeping Philosopher". Heraclitus is famous for his insistence on ever-present change in the universe, as stated in the famous saying, "No man ever steps in the same river twice" . He believed in the unity of opposites, stating that "the path up and down are one and the same", all existing entities being characterized by pairs of contrary properties. His cryptic utterance that "all entities come to be in accordance with this Logos" has been the subject of numerous interpretations.
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