Revelation 4:6-9
"And before the throne there was a sea of glass like unto crystal: and in the midst of the throne, and round about the throne, were four beasts full of eyes before and behind. And the first beast was like a lion, and the second beast like a calf, and the third beast had a face as a man, and the fourth beast was like a flying eagle. And the four beasts had each of them six wings about him; and they were full of eyes within: and they rest not day and night, saying, Holy, holy, holy, Lord God Almighty, which was, and is, and is to come. And when those beasts give glory and honour and thanks to him that sat on the throne, who liveth for ever and ever"

Lion - Matthew's account of Christ
Calf - Mark's account of Christ
Man - Luke's account of Christ
Eagle - John's account of Christ

Full of Eyes
- before, prospective vision (The Lord's Coming)
- behind, retrospective vision (The Lord's Death)
- within, introspective vision (Self-examination)

1Corinthians 11:26, 28
"For as often as ye eat this bread, and drink this cup, ye do shew the Lord's death till He come... But let a man examine himself, and so let him eat of that bread, and drink of that cup."