It is rush hour on the 7 train. I’m returning to Manhattan after a meeting in Queens. The subway car is so packed that no one can move, yet somehow people continue to exit and enter the train at each stop. I’m holding the upper railing with one hand, and the straps of my heavy backpack, which I had not been able to remove, are digging deeper and deeper into my shoulders. Suddenly, a wave of blackness and nausea swells up. It breaks but is quickly followed by another. I try to shift my position to relieve the pressure, take deep breaths of the stale subway air, and concentrate on remaining upright, fighting off each wave as it rolls over me. The train pulls into Grand Central, and I somehow manage to squeeze through the bodies and walk onto the platform. I think I’m okay and take a step toward the stairs to the surface. The next thing I know, I am sitting in the middle of the platform with a stranger’s arms supporting me while other commuters stream past us. He has already called for help and stays with me until the MTA officials take over and I thank him and assure him that I am fine. He then merges with the rest of the stream and disappears.