Platonism is a school of thought based on the teachings of Plato, while Stoicism, Epicureanism, and Skepticism are all Hellenistic schools of thought.

The Stoics believed that the universe is governed by reason, or logos, and that humans can live in harmony with the universe by following reason.

The Epicureans believed that the highest good is pleasure, and that humans should seek out pleasures that are natural and moderate.

The Skeptics believed that all knowledge is uncertain, and that humans can never know anything for sure.

Zeno of Citium, the founder of Stoicism, is known for his saying, "Live in accordance with nature".

Epicurus, the founder of Epicureanism, is known for his saying, "Death is not an evil, for it is a natural part of life".

Socrates, a pre-Hellenistic philosopher, is known for his saying, "The unexamined life is not worth living".

Diogenes of Sinope, a Cynic philosopher, is known for his saying, "The only true wealth is the wealth of the soul".

Buddha, a pre-Hellenistic philosopher, is known for his saying, "The wise person is free from all desires".

Socrates, a pre-Hellenistic philosopher, is known for his saying, "The unexamined life is not worth living".

Diogenes of Sinope, a Cynic philosopher, is known for his saying, "The only true wealth is the wealth of the soul".

Buddha, a pre-Hellenistic philosopher, is known for his saying, "The wise person is free from all desires".

Socrates, a pre-Hellenistic philosopher, is known for his saying, "The unexamined life is not worth living".

Diogenes of Sinope, a Cynic philosopher, is known for his saying, "The only true wealth is the wealth of the soul".

Buddha, a pre-Hellenistic philosopher, is known for his saying, "The wise person is free from all desires".