From Chapter 2:
The properly accomplished gallant not only professed to be curiously learned in pipes and tobacco, but his knowledge of prices and their fluctuations, of the apothecaries' and other shops where the herb was sold, and of the latest and most fashionable ways of inhaling and exhaling the smoke, was, like Mr. Weller's knowledge of London, "extensive and peculiar." It was knowledge of this kind that gained for a gallant reputation and respect by no means to be acquired by mere scholarship and learning.

From Chapter 8:
Says the Pipe to the Snuff-box, I can't understand
What the ladies and gentlemen see in your face,
That you are in fashion all over the land,
And I am so much fallen into disgrace.
- William Cowper.
(From a letter to the Rev. John Newton, May 28, 1782.)

"smoking has gone out," said Johnson in talk at St. Andrews, one day in 1773. "To be sure," he continued, "it is a shocking thing, blowing smoke out of our mouths into other people's mouths, eyes and noses, and having the same thing done to us; yet I cannot account why a thing which requires so little exertion, and yet preserves the mind from total vacuity, should have gone out." Johnson did not trouble himself to think of how much the vagaries of fashion account for stranger vicissitudes in manners and customs than the rise and fall of the smoking-habit; nor did he probably foresee how slowly but surely the taste for smoking, even in the circles most influenced by fashion, would revive. Boswell tells us that although the sage himself never smoked, yet he had a high opinion of the practice as a sedative influence; and Hawkins heard him say on one occasion that insanity had grown more frequent since smoking had gone out of fashion, which shows that even Johnson could fall a victim to the post hoc propter hoc fallacy.