For Lessing's main character, Jerry (an eleven-year-old boy), the turning point happens to be the point of no return when he dives into the water for the last time and pushes his way through the tunnel that exists under water. Up until that point, Jerry was seriously practising for the event, but he could always give up, go back to his mother, and stay safe and sound knowing that his life was not in danger. But when he makes that decision that he won't miss this moment in his life, when he decides that he alone must make the effort to fulfill his goal, that is when he can't turn back. Physically, he can't turn back once he's in the tunnel. If he tries to back out, there's more of a chance that he'll get stuck. So, the combination of Jerry actually making up his mind to take charge of the moment and with him actually swimming into the tunnel is the critical moment of no return; no return to his childhood; and, no returning from the consequences of his choice or actions.