Trinity is the object, Matrix is the Context, HelicopterPilot is the role (injected runtime in Matrix).
It's obviously a simplification but overall I think this metaphor expresses the idea of DCI very well. Trinity represents the D (Data), Matrix represents the C (Context) and HelicopterPilot role along with the Helicopter itself (and other objects) represent the I (Interaction).
This example is good as it shows how your software can evolve. Your objects don't need to know upfront that they will play some roles, it's all runtime (as with Trinity and the helicopter).
Can you fly that helicopter?