The Word of God is more than letters on a page. It is how God created all things, He spoke everything into existence from nothing.   It is powerful.  It's taught, memorized and quoted because it's a weapon against the enemy.  Do we really understand the big picture of what God's Word can do when we use it?  
  
The progressive creation of scripture is one of the most amazing things about God's Word.  Over 40 writers from different locations and times in history unknowingly collaborated to create one of the best-selling books of all time.  It's consistent in its message and full of deep mysteries.  

There are examples throughout both the Old and New Testaments of people quoting scripture.  At first glance, it may appear to show their knowledge, but there is something else to see if you look at the pattern.  

The less obvious lessons in scripture are examples others have modeled for us.  One of these things is quoting scripture.  Both the Old and New Testaments have examples of people citing another passage.  The phrase "it is written" appears over 80 times across the Bible.  There are hundreds of other instances where other passages are referenced without using the "it is written" phrase.  

Why is this done, and why should we do it ourselves?  
God's word is powerful. (God spoke everything into existence, Jesus healed people with His words.)

In the devotional book Daily Inspiration from the Lion's Den, Paul Estabrooks tells of a man named Daniel.  After returning from a trip to China, he summarized what he learned from a house church he visited:  

"It numbers several hundred believers who have a lot of persecution over the past years.  I asked them how they had been victorious and even grown in numbers during such terrible experiences.  They quickly replied, telling me three things," he continued.  "First, obedience to the Word of God; second, communication with God, that is, prayer.  And third, love for the brothers and sisters."  

This group memorized one chapter of the Bible every week.  They began doing this because of a lack of Bibles, but continued doing so after they realized the blessing it brought to their lives.  

Do we need to be under persecution with a Bible shortage to benefit from scripture memory?  Nope.  The benefits are many when we consider the power behind God's Word. 

Want to dive deeper on this?  There's a free downloadable Quick Study on this topic in the Bible Study Worksheets Resource Library.  It also includes a list of the 80 places in scripture that use the phrase "It Is Written."