Neville : You know, if you're interested in plants, you should use Goshawk's Guide To Herbology. There's someone in Tibet who's growing gravity resistant trees...
Harry : Neville, no offense, but I really don't care about plants. Now, if there's a Tibetan turnip that will help me breathe underwater for an hour, great. But otherwise...
Neville : I don't know about turnips, but you could always use gillyweed.
Harry : You're sure about this, Neville?
Neville : Absolutely.
Harry : For an hour?
Neville : Most likely.
Harry : "Most likely?"
Neville : Well, there's some debate among herbologists about its effectiveness in fresh water as opposed to salt water...
Harry : You're telling me this now?
Harry : Don't worry about it.