What is Macbeth’s mental state in this monologue?

At Macbeth’s Castle. Macbeth Enters and speaks to Banquo

BANQUO
You’re not asleep yet, sir? The king’s in bed. He’s been in an unusually good mood and has granted many gifts to your household and servants. This diamond is a present from him to your wife for her boundless hospitality.
[He gives Macbeth a diamond.]

MACBETH
Because we were unprepared for the king’s visit, we weren’t able to entertain him as well as we would have wanted to.

BANQUO
Everything’s fine. I had a dream last night about the three witches. At least part of what they said about you was true.

MACBETH
I don’t think about them anymore at all. But when we have an hour to spare we can talk more about it, if you’re willing.

BANQUO
Whenever you like.

MACBETH
If you stick with me, when the time comes,
It shall make honor for you.

BANQUO
I’ll do whatever you say,
as long as I can do it with a clear conscience.

MACBETH
Rest easy in the meantime.

MACBETH
Is this a dagger I see in front of me, with its handle pointing toward my hand? (to the dagger) Come, let me hold you. (he grabs at the air in front of him without touching anything) I don’t have you but I can still see you. Fateful apparition, isn’t it possible to touch you as well as see you? Or are you nothing more than a dagger created by the mind, a hallucination from my fevered brain? I can still see you, and you look as real as this other dagger that I’m pulling out now. (he draws a dagger) You’re leading me toward the place I was going already, and I was planning to use a weapon just like you. My eyesight must either be the one sense that’s not working, or else it’s the only one that’s working right. I can still see you, and I see blood splotches on your blade and handle that weren’t there before. (to himself) There’s no dagger here. It’s the murder I’m about to do that’s making me think I see one. Now half the world is asleep and being deceived by evil nightmares. Witches are offering sacrifices to their goddess Hecate. (speaking to the ground) Hard ground, don’t listen to the direction of my steps. I don’t want you to echo back where I am and break the terrible stillness of this moment, a silence that is so appropriate for what I’m about to do. While I stay here talking, Duncan lives. The more I talk, the more my courage cools. (a bell rings) I’m going now. The murder is as good as done. The bell is telling me to do it. Don’t listen to the bell, Duncan, because it summons you either to heaven or to hell.