To further the discussion of lines and passages spoken by Atticus Finch, Scout and Jim's father explains one day why he has made Jem read to Mrs. Dubose: He wants him to see what real courage is.
Courage is not a man with a gun in his hand. It's knowing you're licked before you begin, but you begin, anyway and you see it through no matter what. You rarely win, but sometimes you do.
After dinner one Christmas, Uncle Jack talks with Atticus about the forthcoming trial of Tom Robinson, suggesting that maybe Atticus could get out of defending Tom. However, Atticus remarks that he must accept responsibility:
...Right. But do you think I could face my children otherwise? You know what's going to happen as well as I do, Jack, and I hope and pray I cna get Jem and Scout through it without bitterness, and most of all, without catching Maycomb's usual disease.
In Chapter 11 Atticus scolds Jem for cutting the tops of Mrs. Dubose's camellias in anger over her derogatory remarks about his father. Atticus tells the children that he regrets that they are the butt of insults,
.."but sometimes we have to make the best of things, and the way we conduct ourselves when the chps are down--well,...maybe you'll look back on this with some compassion and some feeling that I didn't let you down. This case, Tom Robinson's case is something that goes to the essence of a man's conscience--Scout, I couldn't go to church and worship God if I didn't try to help that man."
When Scout counters with "Atticus, you must be wrong..." because "most folks" are of another opinion, Atticus tells her,
"They're certainly entitled to think that, and they're entitled to full respect for their opinions...but before I can live with other folks I've got to live with myself. The one thing that dosen't abide by majority rule is a person's conscience."
Nearly everything Atticus says reflects his values and principles. I'll give you three of the most significant and common ones, and there will be plenty for others to add, I'm sure.
"You never really understand a person until you consider things from his point of view - until you climb into his skin and walk around in it."
This is indicative of Atticus's belief that everyone has a story and deserves respect just for living. He applies this philosophy to some pretty difficult circumstannces: Mayella in the courtroom, Mrs. Dubose as she's villifying both him and his children, the Cunninghams who come to cause trouble (or worse) at the jailhouse, and Bob Ewell spitting in his face. Atticus encourages his kids to follow this principle, and he lives it out in front of them every day.
"Mockingbirds don't do one thing but make music for us to enjoy... but sing their hearts out for us. That's why it's a sin to kill a mockingbird."
This is Atticus's figurative way of saying things that are innocent and harmless and just trying to be who God created them to be should be left alone to make whatever music they're called to make. In the course of this novel, several characters might qualify as mockingbirds; however, the two most obvious are Boo Radley and Tom Robinson. Even Scout sees the comparison at the end of the book, when it is decided not to reveal to the town that Boo was responsible for Bob Ewell's death. He would have been the town hero, but that would have been like releasing the hounds to the fox--in a good but overwhelming way. He would not have been able to withstand all the attention. Tom is another innocent figure who did nothing more than an act of human kindness for a young, lonely girl. That "song" of kindness was cut short and he was sentenced and shot, despite his innocence. Like Atticus says, that's a sin.
The last quote comes at the end of Atticus's closing argument at Tom's trial. The entire speech is worth quoting, but I'm confident you already know the piece:
"Now, gentlemen, in this country our courts are the great levelers. In our courts, all men are created equal. I'm no idealist to believe firmly in the integrity of our courts and of our jury system. That's no ideal to me. That is a living, working reality!
Now I am confident that you gentlemen will review without passion the evidence that you have heard, come to a decision, and restore this man to his family.
In the name of God, do your duty. In the name of God, believe Tom Robinson."
There's more to the speech, of course, but this is a reflection of Atticus's belief in the law, in his fellow man, and in the innocence of his client. Atticus does not believe everyone is innocent, of course; he does, however, believe that innocent people should and can be treated fairly in the name of the law and in the name of God--and despite their skin color.
That should get you started, and don't be surprised if the list gets too long to deal with effectively!