“No one quite knows who or what they are.”
Many people find themselves searching for an identity, finding out what their role is in the world, how they are going to live their life, what they find important. In short: who they are. This search for identity is always an important theme in MGS, and especially in MGS2. Raiden’s identity has been shaped and molded by others, he has been manipulated and controlled, and now he has to find out for himself who he wants to be. ‘Who am I really?’ he wonders, after which Solid Snake responds with this quote. He goes on to remind Raiden that there is no such thing as absolute reality in this world, so you have to find your own truth, and choose your own life.