solution
The Thorn was originally written in Adrift for David Whyld's 2003 Summer Adrift MiniComp, and later ported to ZCode Inform by Eric Mayer, also in 2003. This solution is by David Welbourn, and is based on the Inform version.
Professor Wilkens' Study
>about. i. x scotch. x prof. x fire. x desk. x window.
>ask prof about thorn. ask prof about abbey. ask prof about Joseph.
>ask prof about Christ. ask prof about scotch.
>z. (Continue to wait until Wilkens leaves.)
>open desk. take map. read map. e.
Beside the Road
>x van. x fens. x church. e.
In Front of the Vicarage
>x flagstone. x snow. n.
The Churchyard
>x gravestone. touch it. n.
The End of the Churchyard
>x monuments. touch it. w.
In Front of the Abbey
>x wall. x brush. take sticks. x sticks. w.
The Ruined Wall
>x trash. x bottle. x weeds. x bush. e. e. s. e.
Inside the Church
>x windows. x stairs. u.
Inside the Church Tower
>take book. x book. x window.
>z. (Continue to wait until Rev. Owen appears.)
Inside the Vicarage
>x fireplace. x window. x Owen. put sticks in fireplace.
>x fireplace. x window. x Owen.
>ask Owen about thorn. ask Owen about God. ask Owen about book.
>ask Owen about Christ. ask Owen about beliefs. ask Owen about abbey.
At this point, there should be a interesting dream sequence.
Inside the Vicarage
>x fireplace. x window. w.
The Ruined Wall
>save.
There are at least three endings:
>south. —or— x bud. —or— take bottle. cut bud.