For these reasons, the philosopher avoids the lusts and desires that afflict the soul when it is imprisoned within the body. Philosophy helps release the soul from this prison, guiding it toward what is true and just, and steering it clear of the pleasures and pains of bodily life. Each pleasure and pain is like a rivet that pins the soul to the body, making it less able to escape. A philosopher will break free of these rivets by listening only to reason and preparing for a contented life after death.


The argument that associates the soul with that which is divine, immortal, invisible, incomposite, and invariable, and the body with that which is corporeal, mortal, visible, composite, and variable is known as the Argument from Affinity. This argument takes the formal features of Forms, those properties a Form has by virtue of being a Form, as opposed to the proper features of Forms, those properties a particular Form has by virtue of being that particular Form. All Forms are of a certain type, and the soul is far more similar to this type than the body is. This kind of inductive reasoning is far from being leak-proof, only suggesting rather than definitively proving that the soul is of a certain kind. Nonetheless, the argument has far fewer holes than the Argument from Opposites or the Theory of Recollection. (It is worth noting, though, that Plato does not always maintain that the soul is incomposite. In the Republic, for instance, Plato suggests that the soul is divided into three parts: reason, appetite, and spirit, or will. In this view, it would seem that the soul is divisible into three parts.)

This section finds a good deal of Pre-Socratic philosophy floating about, most notably that of Parmenides, Democritus, and Pythagoras. Parmenides, a figure greatly admired by Plato, is famous for asserting that what is real must be eternal, indivisible, and unchanging. This idea not only deeply informs this argument, but is also likely an inspiration for Plato's Theory of Forms. Democritus is famous for his atomic theory--that all things are made up of simple, indivisible parts. Socrates' assertion that the soul is indivisible probably borrows somewhat from Democritus' theory. Last, Socrates also borrows from the Pythagorean belief in reincarnation and the transmigration of souls. Simmias and Cebes, both Pythagoreans, would have been favorable toward this theory.

It is worth noting the similarities between Socrates' description of the fate of the philosopher's soul after death and the Christian conception of heaven. This is by no means a coincidence. Christian theology was to be deeply informed by Plato's thinking, and his discussion of the soul and the afterlife were particularly influential.

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