Can anyone give me a good quote about the importance of tone when writing a novel?
Tone is the emotional meat of the story. Is the story or novel apathetic, caustic, or sad? The tone sets the whole emotional scene. If you are reading a creative piece of work and there is no emotion within that writing then the reader can't invest emotion into the work. The tone is the emotional coloring of the work. A writing without tone is like a coloring book that has no color.
"When I use a word," Humpty Dumpty said in rather a scornful tone. "It means just what I choose it to mean - neither more or less."
"The question is," said Alice, "whether you can make words mean so many different things."
"The question is," said Humpty Dumpty, "which is to be master - that's all." Lewis Carroll
"Scornful tone" indicates the emotion of Humpty Dumpty. The quotation is less meaningful unless the reader can determine the emotions of the characters speaking.
Without tone in a creative writing it would be very difficult to extract the meaning the author is trying to relate to the reader. The tone tells us whether the book is funny, sad, or hundreds of other emotions a reader can interpret in a story.