Doyle: "So how long has it been between sunsets?"
Angel: "200 years, give or take."
Doyle: "Well you got to be feeling pretty damn good then, huh? I mean this ring "“ changes everything, don't it? - Yeah, it's spectacular, I know. But I do promise that there will be another one exactly like it tomorrow."
Angel: "Not for me."
Doyle: "What are you saying? That the city will be hit by a meteor before tomorrow night or"¦"
Angel: "No."
Doyle: "No. It's to horrible to say the other. I can't even bring myself to say the other."
Angel: "I'm not going to wear the ring."
Doyle: "That was the other. - You got a real addiction to the brooding part of life. Anyone ever tell you that?"
Angel: "Once or twice."
Doyle: "Care to explain? - I mean this ring is your redemption. It's what you've been waiting for."
Angel: "nah, it just looks like it.'
Doyle: "Angel, man, think what you're saying."
Angel: "I have. I've thought of it from every angle, and what I figure is I did a lot of damage in my day, more than you can imagine."
Doyle: "So what, you don't get the ring because your period of self-flagellation isn't over yet? I mean think of all the daytime people you could help between 9 and 5."
Angel: "They have help. The whole world is designed for them, so much that they have no idea what goes on around them after dark. They don't see the weak ones lost in the night, - or the things that prey on them. And if I join them, maybe I'd stop seeing, too."
Doyle: "And who'd look out for all the insomniacs?"
Angel: "I was brought back for a reason, Doyle, and as much as I would like to kid myself, I don't think it was for 18 holes at Rancho."
I always thought that was sort've weak reasoning. If he said something about Angelus instead or in addition to this it would have made more sense.