Here's Woody's Isaac talking with Yale in Manhattan:
YALE: I'm not a saint, OK?
ISAAC: You're too easy on yourself. Don't you see?
You're... You rationalise everything. You're not honest with yourself.
You talk about you wanna write a book, but in the end you'd rather buy a Porsche.
You cheat a little bit on Emily and you play around the truth with me.
The next thing you know you're in front of a Senate committee naming names.
YALE: You are so self-righteous. I mean, we're just people. We're just human beings.
You think you're God!
ISAAC: I gotta model myself after someone.
You just can't live the way you do. It's all so perfect.
Jesus, what are future generations gonna say about us? My God!
You know, someday we're gonna be like him. [pointing to the skeleton of a caveman in the room]
And he was probably one of the beautiful people, dancing and playing tennis.
And now look. This is what happens to us.
You know, it's important to have some kind of personal integrity. I'll be hanging in a classroom one day and I wanna make sure when I thin out that I'm... well thought of.
And here is a monologue from Isaac near the end of the film, shortly after the scene above:
And here's Dostoyevsky's Ivan speaking to Alyosha in The Brothers Karamazov:
I've been sitting here now, and do you know what I was saying to myself? If I did not believe in life, if I were to lose faith in the woman I love, if I were to lose faith in the order of things, even if I were to become convinced, on the contrary, that everything is a disorderly, damned, and perhaps devilish chaos, if I were struck even by all the horrors of human disillusionment--still I would want to live, and as long as I have bent to this cup, I will not tear myself from it until I've drunk it all! ....
There is still an awful lot of centripetal force on our planet, Alyosha. I want to life, and I do live, even if it be against logic. Though I do not believe in the order of things, still the sticky little leaves that come out in the spring are dear to me, the blue sky is dear to me, some people are dear to me, whom one loves sometimes, would you believe it, without even knowing why; some human deeds are dear to me, which one has perhaps long ceased believing in, but still honors with one's heart, out of old habit. Here, they've brought your fish soup -- help yourself. It's good fish soup, they make it well. I want to go to Europe, Alyosha, I'll go straight from here. Of course I know that I will only be going to a graveyard, but to the most, the most precious graveyard, that's the thing! The precious dead lie there, each stone over them speaks of such ardent past life, of such passionate faith in their deeds, their truth, their struggle, and their science, that I -- this I know beforehand -- will fall to the ground and kiss those stones and weep over them -- being wholeheartedly convinced, at the same time, that it has all long been a graveyard and nothing more. And I will not weep from despair, but simply because I will be happy in my shed tears. I will be drunk with my own tenderness. Sticky spring leaves, the blue sky -- I love them, that's all! Such things you love not with your mind, not with logic, but with your insides, your guts, you love your first young strength.