And all three stood and wept. Even the Lion wept: great Lion-tears, each tear more precious than the Earth would be if it was a single solid diamond....
"Son of Adam," said Aslan, "go into that thicket and pluck the thorn that you will find there, and bring it to me."
Eustace obeyed. The thorn was a foot long and sharp as a rapier.
"Drive it into my paw, son of Adam," said Aslan, holding up his right fore-paw and spreading out the great pad toward Eustace.
"Must I?" said Eustace.
"Yes," said Aslan.
Then Eustace set his teeth and drove the thorn into the Lion's pad. And there came out a great drop of blood, redder than all redness that you have ever seen or imagined. And it splashed into the stream over the dead body of the King.
--C.S. Lewis, The Silver Chair