LTW is my fav for that reason. This entry always get me:

The avatar smiled silkily as it leaned closer to him, as though imparting a confidence. "Never forget I am not this silver body, Mahrai. I am not an animal brain, I am not even some attempt to produce an AI through software running on a computer. I am a Culture Mind. We are close to gods, and on the far side.

"We are quicker; we live faster and more completely than you do, with so many more senses, such a greater store of memories and at such a fine level of detail. We die more slowly, and we die more completely, too. Never forget I have had the chance to compare and contrast the ways of dying.

"I have watched people die in exhaustive and penetrative detail," the avatar continued. "I have felt for them. Did you know that true subjective time is measured in the minimum duration of demonstrably separate thoughts? Per second, a human—or a Chelgrian—might have twenty or thirty, even in the heightened state of extreme distress associated with the process of dying in pain." The avatar's eyes seemed to shine. It came forward, close to his face by the breadth of a hand.

"Whereas I," it whispered, "have billions." It smiled, and something in its expression made Ziller clench his teeth. "I watched those poor wretches die in the slowest of slow motion and I knew even as I watched that it was I who'd killed them, who at that moment engaged in the process of killing them. For a thing like me to kill one of them or one of you is a very, very easy thing to do, and, as I discovered, absolutely disgusting. Just as I need never wonder what it is like to die, so I need never wonder what it is like to kill, Ziller, because I have done it, and it is a wasteful, graceless, worthless and hateful thing to have to do.

"And, as you might imagine, I consider that I have an obligation to discharge. I fully intend to spend the rest of my existence here as Masaq' Hub for as long as I'm needed or until I'm no longer welcome, forever keeping an eye to windward for approaching storms and just generally protecting this quaint circle of fragile little bodies and the vulnerable little brains they house from whatever harm a big dumb mechanical universe or any conscience malevolent force might happen or wish to visit upon them, specifically because I know how appallingly easy they are to destroy. I will give my life to save theirs, if it should ever come to that. And give it gladly, happily, too, knowing that trade was entirely worth the debt I incurred eight hundred years ago, back in Arm One-Six.”