General- Ugin explains the Eldrazi

"The Eldrazi titans do not dwell in physical space," said Ugin. "They are creatures of the Blind Eternities, and it is in the Eternities that they remain."

"Until they manifest physically, you mean?"

"No," said Ugin. "I meant what I said. Ulamog remains in the Eternities."

"Then what did I see heading toward Sea Gate?"

"You saw a portion of him," said Ugin. "A projection. Imagine that you reach your hand into a pond. The fish below the surface sees a five-headed monster, and cannot perceive the man attached to it. It mistakes a hangnail for an eye because the truth is beyond its imagining. You see?"

"And when you trapped them . . ."

"Like driving a spike through the hand," said Ugin. "The man will not die, but neither will he trouble other ponds. 'Killing' Ulamog's physical form would be like cutting off the hand. The man might be diminished, but he would survive—and he would be freed."
...
"This . . . hand metaphor," said Jace. "It's describing the three titans. What about all the others? Does killing them free them too? Are there thousands of Eldrazi loose in the Eternities now?"

"Suppose the man reaches his other hand into the pond," said Ugin. "Does the fish face one monster, or two?"

Jace's patience for this method of imparting information was minimal, but he tried to give the dragon's question-answers due consideration.

"The fish sees two beings," he said, after a moment. "But they're part of one whole."

"Suppose the man has a hundred hands," said Ugin. "Or a million."

Understanding dawned. A wave of nausea overtook him.

"You're saying they're connected. Ulamog's brood aren't really spawn. They're . . . appendages."

"More like cells," said Ugin. "Organs, in the case of some of the larger ones. But all of them are replaceable—sub-lives that come into being, fulfill their function, and die or are reabsorbed, without diminishing the whole."

"So killing them does nothing, other than keeping them from killing you."

"Ultimately, no," said Ugin.


(The Revelation at the Eye)