What is the explanation for this example of figurative language from The Scarlet Letter by Nathaniel Hawthorne ?
"He now dug into the poor clergyman's heart, like a miner searching for gold; or, rather, like a sexton delving into a grave, possibly in quest of a jewel that had been buried on the dead man's bosom, but likely to find nothing save mortality and corruption" (Hawthorne 117). - Simile
This passage comes at the beginning of Chapter X of The Scarlet Letter. Previously in Chapter IV after his wife has recognized him, Roger Chillingworth has an interview with Hester Prynne in the prison. During this interview, Chillingworth vows to find the father of Hester's child,
"There is a sympathy that will make me conscious of him: I shall see him tremble. I shall feel myself shudder, suddenly and unawares. Sooner or later, he must needs be mine."
Now, in Chapter X, Chillingworth who has suspected the Reverend Dimmesdale of being the adulterer and father of little Pearl, ingratiates himself in the home of Dimmesdale as his physician. Chillingworth feigns attendance upon his patient by asking the minister probing questions in the hope that Dimmesdale will reveal the workings of his conscience, a conscience that he guards closely.
Chillingworth is obsessed with the desire to coerce Dimmesdale to reveal the inner workings of his closely guarded heart. He is compared to the miner seeking the treasure of gold, or better yet, the sexton who stealthily digs at night in the dangerous hope of uncovering a valuable jewel from a grave. Chillingworth goes where he should not, probing the heart, the concience of Arthur Dimmesdale. But in seeking the secrets of Dimmesdale's soul, Chillingworth finds nothing but human mortality and sin.