Identify the topic sentence: Where is the topic sentence? 6. The opening of doors is a mystic act: it has in it some flavor of the unknown, some sense of moving into a new moment, a new pattern of the human rigmarole. It includes the highest glimpses of mortal gladness: reunions, reconciliations, the bliss of lovers long parted. Even in sadness, the opening of a door may bring relief: it changes and redistributes human forces. But the closing of doors is far more terrible. It is a confession of finality. Every door closed brings something to an end. And there are degrees of sadness in the closing of doors. A door slammed is a confession of weakness. A door gently shut is often the most tragic gesture in life. Everyone knows the seizure of anguish that comes just after the closing of a door, when the loved one is still near, within sound of voice and yet already far away.