The Open Book
The Bible, revealing the truth of God's word to us.
From Ecclesiastes chapter 4 vs 12 "A rope made of three cords is hard to break". The strength of St John's lies in us all working together with a common purpose.
From Revelation chapter 4 vs 6-10, where animals are representative of the four Gospel writers - in this case, of course, John.
Representing the Holy Spirit, truth, wisdom, power, purity and peace.