Our Scripture reading today is Luke 4:31-32, "And came down to Capernaum, a city of Galilee, and taught them on the sabbath days. And they were astonished at his doctrine: for his word was with power."
The Lord Jesus words had great power due to the fact that He was and is the Word.  John 1:1, "In the beginning was the Word, and the Word was with God, and the Word was God."  The people hearing Jesus teach had for sure never heard anyone like Him.  Verse 32 tells us they were astonished at what they were hearing.  It was the most amazing teaching time they had ever been a part of.  There was weight to every word He said.   
A life can only be changed by the power of the Word of God.  Our words will only accomplish very little compared to the life altering power of God's Word.  1 Thessalonians 1:5, " For our gospel came not unto you in word only, but also in power, and in the Holy Ghost, and in much assurance; as ye know what manner of men we were among you for your sake."  Romans 10:17, "So then faith cometh by hearing, and hearing by the word of God."  We should be praying for opportunities to use God's Word in our every day conversations.  It will not return void!