Bleak House by Charles Dickens

Mr. Bucket and his fat forefinger are much in consultation together under existing circumstances. When Mr. Bucket has a matter of this pressing interest under his consideration, the fat forefinger seems to rise, to the dignity of a familiar demon. He puts it to his ears, and it whispers information; he puts it to his lips, and it enjoins him to secrecy; he rubs it over his nose, and it sharpens his scent; he shakes it before a guilty man, and it charms him to his destruction. The Augurs of the Detective Temple invariably predict that when Mr. Bucket and that finger are in much conference, a terrible avenger will be heard of before long.

Otherwise mildly studious in his observation of human nature, on the whole a benignant philosopher not disposed to be severe upon the follies of mankind, Mr. Bucket pervades a vast number of houses and strolls about an infinity of streets, to outward appearance rather languishing for want of an object. He is in the friendliest condition towards his species and will drink with most of them. He is free with his money, affable in his manners, innocent in his conversation--but through the placid stream of his life there glides an under-current of forefinger.