Plato's dialogue begins in the prison where Socrates awaits his execution, delayed because of a sacred mission to Delos. His disciples Simmias and Cebes gather around him, leading to a profound discussion about the legitimacy of suicide and the true nature of death, which Socrates defines as the separation of the soul from the body. Because the senses constantly deceive and distract the mind from truth, the philosopher spends a lifetime practicing this very separation, purifying the soul from bodily appetites.
To counter the fear that the soul might vanish like smoke upon leaving the body, Socrates introduces several proofs. First, he argues from the cyclical nature of the universe that opposites generate opposites, meaning life and death succeed one another in an endless circle. Second, he presents the doctrine of reminiscence, demonstrating that human beings possess innate knowledge of absolute concepts like equality and beauty, which they must have acquired in a pre-existent state before birth.
Simmias and Cebes raise serious objections, comparing the soul to a harmony of the lyre that perishes when the instrument breaks, or suggesting that the soul might outlive several bodies only to wear out eventually and perish. Socrates pauses to warn his friends against misology, the hatred of reasoning, urging them to rely on rigorous argument rather than despair. He then refutes the harmony theory by showing that the soul rules and restrains the body rather than merely following it as an effect.
Addressing the deeper problem of generation and corruption, Socrates describes his youthful disillusionment with physical science and his turn to the theory of ideas. He argues that things are beautiful through the presence of absolute beauty and alive through the presence of life. Because the soul is inseparably linked to life, it can no more admit death than the number three can admit the even.
Having established the immortality of the soul, Socrates concludes with a grand mythological description of the earth, its subterranean rivers, and the final judgment where pure souls ascend to divine realms while the incurable are cast into Tartarus. As the sun sets, he calmly drinks the hemlock, leaving his friends with a final injunction to care above all for their own souls.
