An inspector calls

What is the significance of the Inspector’s cue to enter the stage? The moment before the Inspector enters the stage, Mr. Birling is talking to his future son-in-law Gerald and his biological son Eric. He is lecturing them about a man's role in society and how a real man should always look after himself and make his own way, "But take my word for it, you youngsters - and I've learned in the good hard school of experience - that a man has to mind his own business and look after himself and his own" (p. 10 ll. 6-9). The Inspector interrupts Mr. Birling’s sermon of advice when he rings the front doorbell in the middle of Mr. Birling’s sentence. It is a kind of moral ambivalent when Mr. Birling proclaims how the two young men should conduct themselves when Mr. Birling himself is full of shortcomings and has made a huge mistake.