While arguing with Thornton about his influence over his workers, Margaret offers this allegory about a man who raised his son improperly.
He had a son—an overgrown man with the unexercised intellect of a child, whom he had kept up in that strange way, in order to save him from temptation and error. But, of course, when this great old child was turned loose into the world, every bad counsellor had power over him. He did not know good from evil. His father had made the blunder of bringing him up in ignorance and taking it for innocence; and after fourteen months of riotous living, the city authorities had to take charge of him, in order to save him from starvation.
Just before this, Thornton admits to the Hales that he views his workers like children. Because children thrive best under firm, consistent authority, Thornton strives to be "an autocrat" at work, and though he aims to rule wisely and justly, he doesn't believe he owes his workers explanations for his actions, any more than a parent would owe a small child; he expects them to blindly obey. When Mr. Hale observes that Milton workers seem more like willful adolescents than obedient children, Margaret steps in with her allegory.
Clearly, the father in this allegory is meant to be Thornton (or a manufacturer like him), and the overgrown child represents a factory worker. By behaving autocratically, the father/employer gives the child/employee no opportunity to develop intellectually or morally. That means that when this ignorant child/employee ventures out in the world (like employees deciding to protest working conditions), he is susceptible to bad influences, not knowing any better. Resorting to "riotous" behavior like strikes and riots, then, the child/employee ends up needing more intervention and support than before, to "save" him from ruin.
With this allegory, Margaret argues that Thornton should exercise more authority over his workers, not less, specifically in order to influence their morals and help them make better choices. While this is a pro-worker, progressive point of view, it's also a distinctly Victorian form of paternalism—the employer is a father who's responsible for shaping and guiding his "children." Margaret offers this allegory as an alternative to the class-conflict model of the employer-employee relationship that Thornton takes for granted, one she sees as benefiting both manufacturer and worker.
