Unseen Visions

Background
''After discovering that Dexion has become blind, I've had to secure alternate means to decipher the Elder Scrolls and locate Auriel's Bow. It's been suggested that I might be able to read the Elder Scrolls myself if I use an ancient technique performed by the original Moth Priests. I'm now on my way to a place known as the Ancestor Glade to discover the origin of the mysterious ritual.''

Walkthrough
After retrieving the other two Elder Scrolls, return to Dexion. Tell him both Elder Scrolls have been retrieved and he will go on to tell you that he can no longer read them as he has gone blind from reading the first per lack of preparation. He will then explain the Ritual of the Ancestor Moth that can be performed at Ancestor Glade, southeast of Falkreath.

Ancestor Glade
Head to Ancestor Glade, located east of Angi's Camp. Enter the cave and proceed deeper past the foliage and over the felled tree trunk. The tunnel will open into an enormous picturesque cavern. Walk down to the bottom of the cavern by the stone pillars and take the Draw Knife from center of the large rock. Use the Draw Knife to collect some bark from one of the surrounding Canticle Trees.

Next, attract 7 Ancestor Moth swarms, they can be obtained by simply walking around the cave and running into each swarm.

Reading the Elder Scrolls
Once all 7 have been attracted, stand in the column of light to read the Elder Scroll (Blood). Vision will be engulfed by a blinding light as the other scrolls are read and a map will begin to form with each reading that depicts a location somewhere between Markarth and Solitude.

After reading the scroll, speak to Serana and tell her the visions about the cave far on the western edge of Skyrim. This appears to be the location of Auriel's Bow. This completes the quest and immediately starts the next, "Touching the Sky".

Upon exiting the conversation, several Vampires or Dawnguard (depending on who has been sided with) will have followed the Dragonborn to the cave and will attack. Once they have been defeated exit out of the cave and head to Darkfall Cave.

Trivia

 * Despite the fact that this is the ritual used to read the Elder Scrolls, reading the Elder Scroll (Dragon) or the Elder Scroll (Sun), even with Canticle Bark in one's inventory and a full swarm of Ancestor Moths, the player will only experience a "default" reading and temporary blindness.
 * With the Alchemy perk Green Thumb, the Dragonborn will be able to harvest two pieces of Canticle Bark. One has a value and weight of 0, the other has a weight of 0 and value of 350. One can be used as a decorative or collectors item, the other sold for a healthy price.

Bugs

 * While searching for the moth swarms, a second follower may disapear.  Reloading from a previous save will restore the follower (experienced while having Serena and J'zargo)
 * One may not be able to take the draw knife. This can be solved by reloading from a previous save.
 * If you enter the Ancestor Glade during this quest without Serana for any reason, upon trying to exit the cave after reading the Elder Scroll, the door will be closed and unable to open. Talking to her forwards the quest and opens the door, but first you have to escape the room itself.
 * Solution: Glitch through the wall a little ways to the left of the door, and then glitch back into the corridor behind the door
 * Solution: Reload a previous save and enter with Serana.
 * Solution: If you find Serana stuck just inside the entrance to the ancestor glade, you can force her past the iron gate by standing close to her and waiting for her to move away. Takes a while but once she is beyond the gate you will be able to talk to her after reading the scrolls.
 * Solution: you may also enter the command tcl pass through the door and exit to skyrim Serana will spawn next to you then.
 * After reading the blood scroll in the ring of light, you may find that all command controls (movement, jumping, etc.) have been disabled except for hard menu (load/exit menu) and the ability to switch from first person to third person views. Loading a prior save may fix the problem, but typically you will have to use console commands to progress the objective.
 * The moths may not follow you.
 * The bark can't be collected.
 * Solution: Use the console commands: 'player.additem xx0191b7 7' (to add the Canticle Barks) then: 'setstage DLC1VQ06 30' (next stage of the quest), then just continue the quest, where "xx" is the load order for the DLC Dawnguard (typically 02).
 * After collecting the moths and standing in the circle of light, the player is incapable of reading the required Elder Scroll. Instead, the player is brought to the standard reading screen and is given the option to turn the pages left and right. However, no visual appears for the scroll whilst in this screen, and the player is incapable of finishing the quest.
 * The bug appears to be related to the Hearthfire DLC, uninstalling the DLC before entering the soul cairn then re-installing after you have acquired the Scroll appears to fix the bug.
 * Possible solution: Reload a previous save.
 * This glitch appears to be related to a bug with the item itself. It may be fixed by opening the console and removing then reading the Elder Scroll (Blood). This may be accomplished by using the command 'player.removeitem 020118F9 1' followed by 'player.additem 020118F9 1'.
 * Should the above fixes not work, a third solution is to identify the stage of the quest your on with console command < sqs DLC1VQ06 >, and then forwarding to the next stage of the quest with command < setstage DLC1VQ06 (STAGE #) >. This should trigger the cinematic that was glitched on the scroll itself. However, it should be noted that this DID NOT remove the glowing orb around the player after collecting the moths.
 * Possible solution for Xbox 360: (reload a previous save and do the following) Before retrieving the blood elder scroll exit and re-enter the soul cairn then retrieve it. This should hopefully correct the bug.
 * Sometimes Serana is gone because the Quest Marker sends you just in and ouside the cave.