Previously in Chapter 4 of Silas Marner, the dissolute Dunstan Cass has rashly ruined his brother's horse that he was sent to sell, and having already considered robbing Marner, he sets off on his "remarkable feat of bodily exertion" of walking home by way of Marner's humble dwelling while he devises his devious plan.
As he approaches Marner's dwelling, Silas Marner himself is not far away. However, Marner has all the confidence in his security of one who has lived long a life apart from the communion of others. This state explains
...why his mind could be at ease, though he had left his house and his treasure [the piece of pork] more defenceless than usual.
After having set up his pork to roast, the miser remembers a piece of "very fine twine" that will be indespensable to his 'setting up' a new piece of work in his loom" on the next day, so he goes out rather than waste time with this errand in the morning. And, because there is a thick and damp fog, Marner does not bother to undo his well-tied string and delay his supper.
Before Marner returns from his errand, there is no further mention of Dunstan Cass. So, when "to his short-sighted eyes," Marner finds everything as he has left it, except that his little cottage has a welcoming warmth to it because of the fire, the reader is uncertain whether Cass has completed his nefarious plan, a fact that creates suspense. And, thus, the narration continues through Marner's perspective of his narrow security. For, Eliot describes the isolated and simple soul of Marner whose own footprints erase others as crosses the threshold to warm himself, considering the length of time until he "drew out his guineas" to delight in them.
Diverting the reader further into the consciousness of Marner's mind, the narration describes the introspection of the weaver as he incredulously discovers the empty, dark hole where hiterto his money has lain.
The sight of the empty hole made his heart leap violently, but the belief that his gold was gone could not come at once—only terror, and the eager effort to put an end to the terror. He passed his trembling hand all about the hole.... At last he shook so violently that he let fall the candle, and lifted his hands to his head, trying to steady himself, that he might think.
With vivid imagery, too, Eliot also builds emotional intensity:
A man falling into dark waters seeks a momentary footing, even on sliding stones; and Silas, by acting as if he believed in false hopes, warded off the moment of despair.
Certainly, the contrast in narrative style of the dispassionate description of the conniving Dunstan Cass and the quiet Marner complacent in his sense of security with the "violent soul" later terrorized by the theft of his gold and disruption to his secure life serves to create suspense, as well.