Philosophy spans the reaches of the human mind in countless topics, but is often divided into three main branches: metaphysics, the study of the nature of existence; epistemology, the study of knowledge and truth; and ethics, the study of morals. One of the first philosophers to look at these fields is Plato (427BCE-347BCE), whose writings are incredibly influential. Plato’s work lays the fundament for philosophy because of his cohesive contributions to the fields of metaphysics, epistemology, and ethics.
Firstly, Plato’s work with Forms greatly influences metaphysics. He contributes the idea of the Forms which exist as “eternal and perfect ideals that exist in an unchanging, perfect heaven” (via Velasquez, 2002, p. 84).  The Forms contrast with worldly matter; this contrast leads to Plato’s next contribution to metaphysics, his concept of “Two Worlds. ” Plato divides reality into the worlds of senses and forms, the latter of which he considers to be true reality and where the soul resides.
Finally, Plato’s description of the tripartite human soul greatly influences St. Augustine’s religious work on Christianity 800 years later. Therefore, Plato’s Forms helped shape metaphysics. Secondly, Plato’s Forms and myths built the foundation for epistemology. Plato argues that due to the soul’s unchanging nature, the process of “learning” is the soul’s recollection of knowledge. He also provides two myths, both closely related to his metaphysical works.
In the first, the Chariot Allegory, Plato describes a charioteer en route to heaven, in which there exists “true reality [the forms] with which real knowledge is concerned ” (as cited by Velasquez, p. 84). The journey is impeded by an unruly horse that represents ignobility. The concept of the journey’s difficulty is mirrored, finally, in the Allegory of the Cave, which discusses ignorance and the escape thereof. Thus, Plato’s myths form the basis of epistemology. Finally, Plato’s work in ethics regarding justice is among the first and most influential.
Firstly, he defines justice as the balance between the three parts of the tripartite soul. Thus, his justice theory states that justice in both the state and the individual is defined by “harmony between the various parts for the good of the whole” (Velasquez, 2002, p. 630). This justice theory shows cohesiveness with Plato’s tripartite theory of the soul. Finally, Plato associates justice with merit: individuals are treated proportionally to their talents and accomplishments. Hence, Plato’s philosophies regarding justice form the starting point for the field of ethics.
In conclusion, Plato’s writings act as a basis and connection for the three main branches of philosophy: metaphysics, through his Forms; epistemology, through his myths; and ethics, through his justice theory. His influence on philosophy and society is expansive and, as such, Plato is one of the most significant philosophers. That his ideas are still being taught to modern day shows the true nature of philosophy: to pose questions so profound that they cannot be answered 2500 years later.