How can I take the spell box near the base of the lighthouse?

Hint 1 of 4:

You can't *take* the box.

Hint 2 of 4:

Read your manual to learn about spell boxes.

Hint 3 of 4:

You don't have your spell book with you.

Hint 4 of 4:

So if you open the box, it will be cast on the nearest thing -- Ernie.