Plato
Plato was one of the most influential philosophers in history. He was born around 428 BCE and died in 348 BCE, living to be approximately 80 years old. Plato studied under Socrates before establishing his own school of philosophy called the Academy. His writings are some of the earliest examples of philosophical thought that still influence modern ideas today.
One major concept explored by Plato is his theory of forms, or ideas," which suggests that there exists a realm beyond physical reality where perfect versions of everything exist, such as justice, beauty, goodness, etc. According to this theory, we can only gain knowledge about these abstract concepts through contemplation and reason rather than sensory experience alone. This idea has had an enormous impact on Western Philosophy over time, with many subsequent thinkers building upon it, including Aristotle, who disagreed with certain aspects but accepted its core principles nonetheless.
In addition to exploring metaphysical questions related to knowledge and existence, Plato also wrote extensively on ethics and politics, particularly advocating for a utopian society ruled by philosopher-kings; individuals who have attained wisdom through their understanding of truth and virtue as well as possessing political power at the same time. Ultimately, though, he believed that true happiness could only be achieved when people act according to what they know is right rather than just following arbitrary laws without any moral consideration whatsoever.