Life! This is Jesus Christ's explanation of why the word of our Lord is so satisfying. It transfuses our spirit which allows us to live our lives for something other than our own flesh.

John 6:63

It is the Spirit who gives life; the flesh profits nothing. The words that I speak to you are spirit, and they are life.

http://www.biblegateway.com/passage/?search=john6:63&version=NKJV