You consider reading it, but you're more interested in the metal contraption. Replacing the book, you search for the room's source of light, and find a lantern hanging above the entrance. You take it down and light the candle, then set the lantern on the floor. You inspect the metal sphere a moment before setting it over the candle.
The room darkens, but tiny points of light dot the walls in what you realize is a representation of the stars! You pick out Medeira, the train of her wedding gown drawn by a scoop of stars, and marvel at the model's accuracy. Glancing around, you frown as a set of stars looks unfamiliar to you. You've never seen these stars in the night sky. Walking over to them, you trace invisible lines between them... forming the outline of a tree! You narrow your eyes, but the smooth walls show no sign of a tree besides the points of light. You feel about within the imaginary lines, applying pressure. You are rewarded with a click as the very center pushes inward, and the whole wall turns, using the point you touched as its axis.
You quickly blow out the candle, lest it eventually set fire to the Lucian Theology book, snatch the lantern, and then step into the tunnel. It leads to your right and slopes downward. Though its walls are smooth, it's clear this tunnel must have been carved out of the existing stone in the ground... formed by dwarves, then, with their innate ability to mold small amounts of rock at a time. The air grows colder as you descend farther and farther. You begin to wonder how difficult the return trip will be going uphill instead of down... you've traveled quite a ways. Ah, but you have the telegem; at the very least, it won't be difficult to get back to the library. Still, you probably shouldn't be down here, and have no idea where it might deposit you. Just as your second-guessing nearly causes you to pull out the telegem, the tunnel seems to come to a dead end. A strangely glittering painted tree decorates the wall next to a lever. You push it and the rock wall swings inward.
A blast of chill, dank air causes you to gasp, but you walk through to a much wider tunnel, your lantern struggling to light the area. Supports line this tunnel, and you notice a track built into the center of the floor - it's an abandoned mine shaft! The rock door behind you slides back into place with an ominous boom, leaving no apparent way back. You lick your lips.
Lifting your lantern to look around, you notice a strange glitter on the far wall. You step closer to find another shimmering tree, this time with an arrow pointing right. With no better direction, you follow its leading. Every time the shaft has a turn, you find the telltale sparkle of a tree with an arrow pointing the way. To what, you wish you knew.
Eventually, the shafts give way to caves. The arrows lead you to a cave whose floor gives way to water. A nearby boat bears the now-familiar glittering tree.
You take it and use the accompanying pole to push the boat along the cave's path. Your bluish lantern reflects off beautiful speleothems of dripstone, striated flowstone, and waving curtains of mineral deposits, some so thin, they're translucent, giving the whole place an ethereal cast. You lift your lantern for a better look and realize the water has its own eerie, but captivating green glow.
Reaching a shoreline, you land your boat beside another like it, and find another shimmering tree on a lever beside a wall.