This tune comes from Handel's Oratorio Solomon and is actually called Sinfonia, opening Act 3 of the work. Composed in 1748, the greater work tells of a suitably mental and wafer thin 'plot'. Act One describes the building and blessing of Solomon's new temple, later beckoning his queen to the cedar groves to 'love beneath the pleasing gloom'. Act Two has the usual operatic argument involving two women who debate who is the mother of a newly-born baby. (Was everyone's memory that short back then?) Act Three involves the Queen of Sheba (i.e. Egypt and Ethiopia) turning up and saying what a swell place Solomon lived in.
That's pretty much it. I don't really see (often) the big difference between some rock music and operatic works like this, as they both involve good music and really terrible lyrics and premises. Sometimes even the best should really just shut up and let the music do their talking. The fact that the words are being transmitted to you by a trained soprano - as opposed to say Axl Rose - doesn't impart them with any real substance.
Handel and Guns and Roses. Now there's a mash-up for you.
This is also available on YouTube.