I'm hoping to clear up some confusion here. I've heard and read in several places that it's a good thing to let a glass of whiskey breathe for a bit before drinking it, to allow it to open up more thoroughly. In fact, the "Nosing and Tasting Course" on this site says, "it is no bad thing to leave your samples open to the air for a while (half an hour, say) to let them breathe and settle."
But I've also been hearing and reading that it's a bad thing to put your whiskey in a decanter, precisely because it exposes the whiskey to air.
This confuses me. Is air a good thing or a bad thing? If letting a glass of whiskey breathe causes the flavors to open up, why wouldn't decanting the whiskey do the same thing? Or is it a case of "too much of a good thing"?
I also enjoy a good wine from time to time, and I know there are tools that can be used to aerate the wine - has anyone tried using similar tools for aerating whiskey?

