The engine, and where the valve goes

Follow it round once. The thing to notice is that the loop never stops at a conclusion. It just comes back to the top with you standing slightly further back than you were.

The demand arrivesYou feel you owethisYou explain andjustifyIt is not acceptedYou comply, or yourupture
The exit is not inside the loop. It sits before the explaining, and lesson four is about it. The diagram shows a loop running through: The demand arrives, then You feel you owe this, then You explain and justify, then It is not accepted, then You comply, or you rupture.