Elder Knowledge (quest)

Walkthrough
Having made it to the The Throat of the World the dragon Paarthurnax will explain that an Elder Scroll will be required to learn a shout, developed by the humans, in ages long gone. All this is the only way to get a chance to face off against Alduin.

Note: Should the Dragonborn already have completed Discerning the Transmundane, having visited the Dwemer Oculory located within the Tower of Mzark in Blackreach, the Elder Scroll should already be in the inventory. Bypassing all of the below steps.

Learn the location of the Elder Scroll
First the location of the Elder Scroll will need to be learned.

(Optional) Talk to Esbern
Either talk to Esbern, at Sky Haven Temple asking about learning the shout Dragonrend, requiring to know the location of the Elder Scroll for that.

(Optional) Talk to Arngeir
Alternately, talk to Arngeir at High Hrothgar and ask about the scroll's location.

Recover the Elder Scroll
Both point to the College of Winterhold. Urag gro-Shub the librarian will give you two books to read on the subject and this will lead to Septimus Signus an expert on Elder Scrolls and the quest Discerning the Transmundane during which the scroll is finally found.

Das Wissen der Alten (Aufgabe)