How does Charles Dickens use imagery in Bleak House?

Imagery:

Mr. Tulkinghorn, sitting in the twilight by the open window, enjoys his wine. As if it whispered to him of its fifty years of silence and seclusion, it shuts him up the closer. More impenetrable than ever, he sits, and drinks, and mellows as it were in secrecy, pondering at that twilight hour on all the mysteries he knows.

And there he sits, munching and gnawing, and looking up at the great cross on the summit of St. Paul’s Cathedral, glittering above a red-and-violet-tinted cloud of smoke. From the boy’s face one might suppose that sacred emblem to be, in his eyes, the crowning confusion of the great, confused city–so golden, so high up, so far out of his reach.