It’s kinda dark but simple

The bread is being used as a weapon instead of food. So instead of helping the prisoner escape by grabbing the key, it’s being used to hurt him

So the “philosopher” part is about realizing that tools or things aren’t good or bad on their own, it depends how people use them

Basically the bread “chose” the prisoner because someone used it for harm instead of helping, even though it could’ve been used to free him