A Key 

to open the door to understanding the Apocalypse.  Start with numbers, colors, and Old Testament references.  Numbers and colors do not require interpretation and Old Testament references are reliable clues.  The bow in Revelation 6:2 is not a weapon but a covenant like the one in Genesis 9:13 .  This helps to identify the rider of the white horse. 

Watch for more pieces that fit.  Blessed is the one who looks.