Myst Island -- The colored books and pages

When you open one of the books and click on the front page, you see a person talking to you. Who is this person? What are they telling you? How does it compare with the person in the other colored book?

There is a colored page sitting next to book of the same color. What should I do with this? Is it from the book next to it?

Who are these people?

And what do they want?

Go back to Myst Island -- The building with the pillars