Two key aspects of Plato's ethical doctrine are found in the Phaedo: the theory of recollection and the theory of forms. Although they differ they're both vital in supporting the other. Before understanding the theory of recollecting, I think a sound understanding of the theory of forms is necessary.
The theory of the forms is hinted at in previous books like the Meno but it isn't until the Phaedo before it is really introduced. The basic idea behind the theory of the forms is that in a sense, there are two realities. According to Plato, there is what we perceive to be "real and what is actually "real . The latter reality is what is actually real. This reality has always existed and will always continue to exist without changing. Nothing is tangible and there is no way to definitively prove their existence but Plato is more than confident they exist. Everything we typically believe to be reality isn't according to Plato. Understanding the forms is what is most important for Plato. Unless you know the form of something, you do not understand what is real. The idea of relativity also illustrates the importance of the forms. Using the example in the Euthyphro, this relat