Quote 1
"I resented it, Harry."
Dumbledore stated it baldly, coldly. He was now looking over the top of Harry's head, into the distance.
"I was gifted, I was brilliant. I wanted escape. I wanted to shine. I wanted glory.
"Do not misunderstand me," he said, and pain crossed the face so that he looked ancient again. "I loved them. I loved my parents, I loved my brother and my sister, but I was selfish, Harry, more selfish than you, who are a remarkably selfless person, could possibly imagine." (35.57-60)
Dumbledore, it seems, wasn't quite strong enough to sacrifice his future for his family, as he was asked to do – one of the reasons why he recognizes Harry as a better man. Harry's selflessness is remarkable; his choice to sacrifice himself is something that most of us wouldn't have been able to do!
Quote 2
"Your point about Wizard dominance being FOR THE MUGGLES' OWN GOOD – this, I think is the crucial point… We seize control FOR THE GREATER GOOD." (18.34)
Whoa, there – this quote from a teenage Dumbledore to teenage Grindelwald is shocking. However, it raises an intriguing question – what is "the greater good"? How, for that matter, do we determine what is good or evil? Why should the two former friends have split, but continued, each in his own way, to hold to similar ideals, but on different sides?
Quote 3
"Master of death, Harry, Master of Death! Was I better, ultimately, than Voldemort?"
"Of course you were," said Harry. "Of course – how can you ask that? You never killed if you could avoid it!"
"True, true," said Dumbledore, and he was like a child seeking reassurance. "Yet I to sought a way to conquer death, Harry."
"Not the way he did," said Harry. […] "Hallows, not Horcruxes." (29)
Again, the question of ends vs. means arises – if Dumbledore and Voldemort had the same goal in mind, does it even matter that they worked towards it in different ways? Harry reassures Dumbledore that it does… what do you think?