Matrix is somewhat avant-garde or 'different' so i would suggest choosing an exotic related text such as the ivory trail. You'd be exploring the evocative and of course exotic aspects of the stimulus and use this to relate it back to the speculation of imaginative journeys.
(Btw i'm assuming you're doing imaginative journeys, because most people who use matrix do this, however if it's physical or inner you'd focus on the more tangible aspects)