"Patriotism is the last refuge of a scoundrel."
from Boswell's Life of Johnson

On over-indulgence with drink, to the extent of becoming a beast: "He who makes a beast of himself gets rid of the pain of being a man."
Anecdotes of the Rvd Percival Stockdale (reprinted in "Johnsonian Miscellanies", edited by G.B. Hill).

"When a man is tired of London, he is tired of life; for there is in London all that life can afford."
from Boswell's Life of Johnson

"A man of genius has been seldom ruined but by himself."
Johnson: Letter to Joseph Baretti

"Knowledge is of two kinds. We know a subject ourselves, or we know where we can find information upon it."
from Boswell's Life of Johnson

"Sir, a woman's preaching is like a dog's walking on his hind legs. It is not done well; but you are surprised to find it done at all."
from Boswell's Life of Johnson

"No man but a blockhead ever wrote, except for money."
from Boswell's Life of Johnson

"A man may write at any time, if he will set himself doggedly to it."
Boswell: Journal of a Tour to the Hebrides

On second marriages: "The triumph of hope over experience."
from Boswell's Life of Johnson

"A decent provision for the poor is the true test of civilization."
from Boswell's Life of Johnson

"No people can be great who have ceased to be virtuous."
Johnson: An Introduction To The Political State of Great Britain

"Much may be made of a Scotchman, if he be caught young."
from Boswell's Life of Johnson

"Human life is everywhere a state in which much is to be endured, and little to be enjoyed."
Johnson: Rasselas [said by the character Imlac]

"A man, Sir, should keep his friendship in constant repair."
from Boswell's Life of Johnson

"No man will be a sailor who has contrivance enough to get himself into jail; for being in a ship is being in a jail, with the chance of being drowned."
from Boswell's Life of Johnson

"Depend upon it, sir, when a man knows he is to be hanged in a fortnight, it concentrates his mind wonderfully."
from Boswell's Life of Johnson

"Sir, I have found you an argument; but I am not obliged to find you an understanding."
from Boswell's Life of Johnson

Definition of "oats": "A grain, which in England is generally given to horses, but in Scotland appears to support the people."
Johnson: A Dictionary Of The English Language. (A selection of definitions can be found here.)

On London: "Sir, if you wish to have a just notion of the magnitude of this city, you must not be satisfied with seeing its great streets and squares, but must survey the innumerable little lanes and courts. It is not in the showy evolutions of buildings, but in the multiplicity of human habitations which are crowded together, that the wonderful immensity of London consists."
from Boswell's Life of Johnson

...much enquiry having been made concerning a gentleman, who had quitted a company where Johnson was, and no information being obtained; at last Johnson observed, that 'he did not care to speak ill of any man behind his back, but he believed the gentleman was an attorney'.
from Boswell's Life of Johnson

"The law is the last result of human wisdom acting upon human experience for the benefit of the public."
Piozzi: Anecdotes

Definition of "pension": "An allowance made to any one without an equivalent. In England it is generally understood to mean pay given to a state hireling for treason to his country."
Johnson: A Dictionary Of The English Language. (A selection of definitions can be found here.)

"We must either outlive our friends you know, or our friends must outlive us; and I see no man that would hesitate about the choice."
Piozzi: Anecdotes

"Exercise!! I never heard that he used any: he might, for aught I know, walk to the alehouse; but I believe he was always carried home again."
Piozzi: Anecdotes

On America: "How is it that we hear the loudest yelps for liberty among the drivers of negroes?"
Johnson: Taxation No Tyranny

"Life is a pill which none of us can bear to swallow without gilding."
Piozzi: Anecdotes