STOICISM
Its founder was Zenon of Cyprus (334-262 BC). The name Stoicism came from the fact that they held their meetings in a columned road (stoa). According to them, fate is a cosmic cycle. A person cannot change fate, they can achieve freedom and therefore happiness by acting in accordance with fate or remaining indifferent. The four virtues that must be found in daily life are wisdom, courage, moderation, and living in harmony with nature. A person who has reached wisdom spreads an inner calm (stoic calm) and goodness to the world. According to the Stoics, virtue and knowledge are identical. They make a distinction between “what is natural” and “what is against nature” and develop the concept of “duty” based on “what is natural”.
The Stoics divide philosophy into three; logic, physics, and morality. Logic is designed as a means of reaching true knowledge. Physics investigates the structure and fundamental laws of the universe. Although they were influenced by Democritus’ materialism, they stayed away from a mechanistic view of nature that excluded purpose because they adopted pantheism. Stoics consider nature and God as identical. The soul is completely dominant over the body, it is a warm breath (pneuma) that holds the body together and spreads throughout the body, and God is a warm breath spread throughout the universe. The soul and matter are not separate, there is only one nature. Humans have a share in the world mind (logos). Human is a microcosm that reflects the macrocosm.
There are three main representatives of the New Stoa (Roman Stoa). These are Seneca, Epictetus (a slave) and Marcus Aurelius (Roman Emperor). Seneca says that humans are sacred to humans.
EPICUREANS
Epicurus (341-270 BC) was born on Samos, a Greek island in the Aegean Sea. He developed an empiricist theory of knowledge, a definition of nature based on atomistic materialism, a theory of evolution, and a view of life aimed at happiness based on the absence of mental and physical pain. He lived a communal life with a group of students, including women and slaves, whom he gathered around him in Athens. They were called garden philosophers. According to them, the state is not a natural institution but a contractual institution that exists for the individual. According to them, we do not need to fear the gods, we do not need to worry about death, if death has come, we do not exist anymore, what is good is easy to obtain, what is terrible is easy to endure. After Epicurus, many Epicureans turned to a one-sided addiction to pleasure. They adopted the principle of "Live in the moment you are in!"
SCEPTICISM
Skepticism is a philosophical approach that views all kinds of knowledge with doubt and argues that it is not possible to reach absolute truth. The most extreme skeptic, Pyrrho (365-270 BC), says that in order to reach mental tranquility (ataraxia), judgment must be suspended (epoche).
NEOPLATONISM
Plotinus (205-270) settled in Rome after studying philosophy in Alexandria. His main work is the "Enneads". His philosophy has inspired all mystics. According to him, only God exists, things in nature emanate from the "One", they are weak reflections of the "One". The first element emanating from the One is Nous. Nous contemplates the "One" as soon as it emerges from it. The soul, which emanates from Nous, also contemplates Nous. We can approach God within our own soul, and unite with the great secret of life. Mystical experience is a personal encounter with God in Western mysticism, namely Judaism, Christianity and Islam, and a complete melting and merging in God or the world soul in Eastern mysticism, namely Hinduism and Buddhism.