Raining all day today, I just had the long walk into work and "Trust me, there's no word for 'crisp' on Ferenginar." comes into my head. What is one of your favorites?
"I regret that we meet in this way. You and I are of a kind. In a different reality, I could have called you friend." -- The Romulan commander in Balance of Terror
"In every revolution, there's one man with a vision." -- Kirk in Mirror, Mirror
Do you know what the trouble is? The trouble is Earth-on Earth there is no poverty, no crime, no war. You look out the window of Starfleet Headquarters and you see paradise. It's easy to be a saint in paradise, but the Maquis do not live in paradise. Out there in the demilitarized zone all the problems haven't been solved yet. Out there, there are no saints, just people-angry, scared, determined people who are going to do whatever it takes to survive, whether it meets with Federation approval or not.
And one from Quark:
Let me tell you something about Hew-mons, Nephew. They're a wonderful, friendly people, as long as their bellies are full and their holosuites are working. But take away their creature comforts, deprive them of food, sleep, sonic showers, put their lives in jeopardy over an extended period of time and those same friendly, intelligent, wonderful people... will become as nasty and as violent as the most bloodthirsty Klingon. You don't believe me? Look at those faces. Look in their eyes.
The first duty of every Starfleet officer is to the truth, whether it's scientific truth or historical truth or personal truth! It is the guiding principle on which Starfleet is based. And if you can't find it within yourself to stand up and tell the truth about what happened, you don't deserve to wear that uniform!
Every one of us has a thousand different kinds of little people inside of us, and some of them want to get out and be wild, and some want to be sad or happy or inventive, or even just go dancing! That's why we all have so many different urges at different times. And all those different little people inside of us: we must never be afraid to take them with us wherever we go. Who knows when we may need one of them to pop up and rescue us from ourselves! Variety, my dear Alex. The great secret is not the variety of life, it's the variety of us.
Mudd: "Human beings do not survive on bread alone ... but on the nourishments of liberty. For what indeed is a man without freedom ... naught but a mechanism, trapped in the cogwheels of eternity."