What does it mean when Pride mentions about Edward turning into a philosopher's stone to infiltrate him? In episode 61, when the fight goes on between Edward and Pride, Kimblee interferes with the mind of Pride. Edward uses this moment to attack Pride by getting into his mind (or body maybe). However, as this occurs, the dialog of Pride to Edward is this:


  he turned himself into a philosopher's stone to infiltrate me?


What does this mean and how it is possible as Edward is not in possession of a philosopher's stone (not sure whether he can do it with a philosopher's stone)?
You have to remember that philosopher's stones are merely the souls of people.

I haven't watched the episode in a while, but I'm fairly certain Edward explains it as using part of his own soul/life force to generate a philosopher's stone.

Edit: found this on the wiki


  Breaking free of his bonds, Edward takes hold of Pride's head and, turning himself once more into a single-souled Philosopher's Stone, forces his way into the Homunculus' psyche.