Law of First Mention

When studying scripture, one valuable tool is The law of first mention.  It says that when seeking revelation on a particular word or topic, use the Bible to explain the Bible.  In other words, find the first place in Scripture that word or doctrine is revealed and study that passage. 

Often the Bible's  first mention of a concept is the simplest and clearest presentation.  

Christ celebrated the Passover meal with his disciples the night before his trial and crucificion.  We read about this in Matthew 26.  The church remembers this ceremony regularly when it celebrates Communion.  

We read of the First Mention of the Passover in Exodus 12.  Moses had the Israelites place blood over their house doorposts and roast and completely eat a lamb.

When you compare the two passages, along with other mentions of Communion in the New Testament, you develop a picture of God's eternal plan that astounds the mind.