Book
In Revelation 10:9, "And I went unto the angel, saying, give me the little book," signifies the faculty of perceiving the quality of the Word from the Lord.
In Psalm 40:7, this signifies the Word. (Apocalypse Explained 299, Coronis 60)
(References: Apocalypse Explained 616)
Revelation 10:10
10
I took the little book out of the angel's hand, and ate it up. It was as sweet as honey in my mouth. When I had eaten it, my stomach was made bitter.