Nothing could be further/farther from the truth

자료: http://www.thefreedictionary.com/farther

Usage Note:
Since the Middle English period many writers have used farther and further interchangeably. According to a relatively recent rule, however, [:]

• farther should be reserved for physical distance and
• further for nonphysical, metaphorical advancement.

Thus 74 percent of the Usage Panel prefers farther in the sentence:

• If you are planning to drive any farther than Ukiah, you'd better carry chains, and

64 percent prefers further in the sentence:

• We won't be able to answer these questions until we are further along in our research.

In many cases, however, the distinction is not easy to draw. If we speak of a statement that is far from the truth, for example, we should also allow the use of farther in a sentence such as Nothing could be farther from the truth. But Nothing could be further from the truth is so well established as to seem a fixed expression.

.... The American Heritage® Dictionary of the English Language, Fourth Edition copyright ©2000 by Houghton Mifflin Company. Updated in 2003. Published by Houghton Mifflin Company. All rights reserved.