I can't give you a page number because I don't know what anthology of version of the play you're reading. I can tell you that this line is in Macbeth, Act V, scene 5, and is spoken by Macbeth:
I have almost forgot the taste of fears:
The time has been, my senses would have cool'd
To hear a night-shriek; and my fell of hair
Would at a dismal treatise rouse and stir
As life were in't: I have supp'd full with horrors;
Direness, familiar to my slaught'rous thoughts,
Cannot once start me.
This speech occurs just before Macbeth learns that his wife has committed suicide. Before saying these lines, he hears women screaming. He says he has forgotten what fear is; until now, everything has seemed to go his way. From this point forward, Macbeth will learn what fear really is.