Sorry for disappearing--shoulder problems again, and this may be shorter than I'd like.
As to the 15 year change, I think that Pratchett simply does it because somehow, he's got to make the baby old enough to challenge Duke Felmet. It is, of course, Granny who weaves the spell (though all 3 have to take part), since Granny is going to be the "head" witch of Discworld. Pratchett does this sort of thing occasionally in other books--less so as time goes on (and he gets better at plotting, I think). But, for example, I think that the inclusion of the Vampire and the Troll in Monstrous Regiment is somewhat akin. He wants to make a point about females, and he doesn't want to limit it to humans.
As to the use of allusions-- my thought (being exceedingly familiar with Macbeth) is that novel works all right, but is a bit odd--quite odd in places if you don't have any idea about Macbeth. And since we have only a tiny glimpse of Lancre before this time, Pratchett uses this book to define the country and the characters which will become more important in later books. Most of the allusions, I think, are just plain fun (like those in Soul Music). If you know that Shakespeare's theatre was The Globe, then it is appropriate that TomJohn & his father call their The Dysk. The same could be said for many (most?) of the allusions--The fool's awkward re-working of Shakespeare's sonnet (Shall I compare thee to a summer's day) which turns into June 14th (IIRC).
The place that I think Pratchett uses the play and the witches most strongly (although Shakespeare's witches are certainly not unique in their character) is by setting up the total difference -- turning the nature of the witches and their powers & responsiblities almost on their head. These witches do not cause evil actions, but rather right the larger evil committed by the Felmets (who are certainly fell types) and protect the land and it's people.
(More comments later, but shoulders have given out completely.)
As to the 15 year change, I think that Pratchett simply does it because somehow, he's got to make the baby old enough to challenge Duke Felmet. It is, of course, Granny who weaves the spell (though all 3 have to take part), since Granny is going to be the "head" witch of Discworld. Pratchett does this sort of thing occasionally in other books--less so as time goes on (and he gets better at plotting, I think). But, for example, I think that the inclusion of the Vampire and the Troll in Monstrous Regiment is somewhat akin. He wants to make a point about females, and he doesn't want to limit it to humans.
As to the use of allusions-- my thought (being exceedingly familiar with Macbeth) is that novel works all right, but is a bit odd--quite odd in places if you don't have any idea about Macbeth. And since we have only a tiny glimpse of Lancre before this time, Pratchett uses this book to define the country and the characters which will become more important in later books. Most of the allusions, I think, are just plain fun (like those in Soul Music). If you know that Shakespeare's theatre was The Globe, then it is appropriate that TomJohn & his father call their The Dysk. The same could be said for many (most?) of the allusions--The fool's awkward re-working of Shakespeare's sonnet (Shall I compare thee to a summer's day) which turns into June 14th (IIRC).
The place that I think Pratchett uses the play and the witches most strongly (although Shakespeare's witches are certainly not unique in their character) is by setting up the total difference -- turning the nature of the witches and their powers & responsiblities almost on their head. These witches do not cause evil actions, but rather right the larger evil committed by the Felmets (who are certainly fell types) and protect the land and it's people.
(More comments later, but shoulders have given out completely.)
