The Two Towers Book 3, Chapter 11
The sun fades as the company travels toward Edoras. Merry asks if they are going to rest and Gandalf tells them that Treebeard would think them very hasty. He plans to travel for a few hours and then break for the rest of the night. Merry doesn't yet know about the battle at Helm's Deep and wants to hear about it. Gandalf tells him that the battle was won, but it marks only the beginning of a long war. When the moon peaks, they stop for the night. Merry and Pippin try to figure out how long it has been since they slept in real beds. Pippin asks him how much Gandalf has changed and they think he is more powerful.
Pippin wonders about the reflective sphere that Gandalf took from the Orthanc. He wants to look at it, but Merry wants to go to sleep. Pippin stays awake. "He tossed and turned and tried to think of something else." Book 3, Chapter 11, pg. 250. This was to no avail. He sneaks off and arrives at the sleeping place of the wizard. He searches through his stuff and eventually finds it. He walks away and looks within it as soon as possible. It holds his eyes and he panics, screaming before long. A voice possesses him that screams at Saruman. Gandalf yells for him to come back. Pippin shakes the possession off and the wizard asks him what happened. He tells him that Sauron came and asked what he was. He said he was a Hobbit. Sauron told him that they would be meeting soon. Gandalf tells him to calm down because Sauron discovered noting of great importance. If anything, now they know that Sauron has not yet found out about the destruction of Isengard. The stone also confirms the relationship between Isengard and Mordor. The stone is called a Palantir. There were seven crafted a long time ago and Sauron must have one of them. They were made to communicate across the great distances of ancient Gondor. Aragorn realizes that this stone must have been the possession of his ancestors. He claims it as its protector and Gandalf gladly gives to him with a warning against using it. Gandalf is happy that he did not look into it first, because he fears that he may have lost a battle of wills with Sauron.
The riders split up to make haste. Eomer and Theoden go one way and Gandalf goes the other with Pippin. As the wizard looks to the sky, he sees the black shape of a Nazgul. The black riders who were unhorsed, have been given new winged steeds. He knows that the creature is looking for hobbits. He whispers to Shadowfax and they speed away. Gandalf speaks to himself and then to Pippin. He tells him that the palantir is older than either Sauron or Saruman. He figures that Saruman found his and was trapped by Sauron one day while he was gazing into it. He chastises Pippin for acting foolishly. Pippin asks about the Nazgul. Gandalf is unhappy about it because it means that Sauron will know about the fall of Isengard sooner than they wanted him to. He does not know whether this information will make the situation better or worse for them. He tells Pippin then that they are not heading back into Rohan, but straight on to Minas Tirith.