There have been many times over the years when I've found quotations that I've liked and have jotted them down in journals/diaries. Some stick with me over time and others are only important for that particular stage. (There are almost always several from Mark Twain.)
I just came across some from a couple years ago...
"We write frankly and freely, but then we 'modify' before we print."
- Mark Twain, Life on the Mississippi
"Of all the animals, the boy is the most unmanageable."
- Plato, Theaetetus
"A baby is an inestimable blessing and bother."
- Mark Twain
"It couldn't have happened anywhere but in little old New York."
- O. Henry, A Little Local Color
"Courage is resistance to fear, mastery of fear - not absence of fear."
- Mark Twain, Pudd'nhead Wilson
"There is only one corner of the universe you can be certain of improving, and that's your own self."
- Aldous Huxley, Time Must Have a Stop
"To love oneself is the beginning of a life-long romance."
- Oscar Wilde, An Ideal Husband
"He was a self-made man who owed his lack of success to nobody."
- Joseph Heller, Catch-22
"The Irish are a fair people - they never speak well of one another."
- Samuel Johnson
"A hen is only an egg's way of making another egg."
- Samuel Butler, Life and Habit
"Thank heaven the sun has gone in and I don't have to go out and enjoy it."
- Logan Pearsall Smith
"Everybody talks about the weather, but nobody does anything about it."
- Mark Twain
"Eats first, morals after."
- Bertolt Brecht
"Vanity is only being sensitive to what other people probably think of us."
- Paul Valery
"Procrastination is the thief of time."
- Edward Young
"The devil can cite scripture for his purpose."
- Shakespeare
"If we resist our passions, it is due more to their weakness than our own strength."
- Francois de La Rochefoucauld
"Contraceptives should be used on all conceivable occasions."
- Spike Mulligan
"All the things I really like to do are either immoral, illegal, or fattening."
- Alexander Woollcott
"All you need in this life are ignorance and confidence, and then success is sure."
- Mark Twain
"Technology...the knack of so arranging the world that we don't have to experience it."
- Max Frisch