The Book of Kells is referred to in the Annals of Ulster as being "The Chief Relic of the Western World." It contains 678 illustrated calf-skin or vellum pages with the last two being without illustration. The major part of the Book was probably written in the Columban Monastery's scriptorum on the island of Iona, in Scotland and was coloured using natural dyes, made by the monks. The ink has not faded in 1000 years.
There is a lot of nonsense talked about the four symbols that are used in the Book of Kells:- LION; MAN; CALF and EAGLE. Most historians say that they are supposed to represent the four Apostles. They do NOT represent the Apostles but represent the Twelve Tribes of Israel, to whom the Apostles were sent, by Christ.
The four symbols are the four Brigade-Emblems of the Twelve Tribes of Israel, who camped around "The Tabernacle" in the wilderness during their "forty year punishment and wandering", in the wilderness under Moses.
The encampment was square, with three tribes camped on each of the four sides. The centre tribe of the three, on each side was the Brigade-Leader, so their standard was the dominant one, on each of the four sides. Those four tribes were Judah; Reuben; Joseph/Ephraim and Dan.
Judah's standard is a LION; Reuben's standard is a MAN; Joseph / Ephraim's standard is a wild-ox CALF (which today has become a Unicorn) and Dan's standard is an EAGLE.
The Irish people are mostly descended from Dan and came to Ireland at various times, under various names, as they migrated by different routes and arrived at different times, having picked up new names along the way. One of those names makes their identity more obvious than the others and that name is the Tuatha de Danaan - the Tribe of Dan; who was the fifth of Jacob/Israel's twelve sons. Jacob/Israel's twelve sons fathered the twelve tribes of Israel.
Prior to the De Danaans were the Nemidhians (Sons of Heaven) who came from Carthage which was a Phoenician Danite settlement or Sanctuary (Nemidh), in what is now Tunisia. The Phoenician sailors of ancient history were mostly Israelites from the tribes of Dan; Gad and Simeon. Phoenicia was a region not a country, just as Europe is a region and not a country.
After the Tuatha de Danaans came to Ireland, there were, at various times, further immigrations of Danites under the name Milesians (sons of Mil, who was a Danite warrior, from which the name milesian later came to mean warrior) and of course later still as Dan-ish Vikings and Norsemen.
The EAGLE is the tribal-standard or ensign/emblem of Dan and the Danites discovered America in the B.C. era and again as Vikings (Eric the Red; Leif Ericsson; etc.), long before Columbus*, and later helped to populate it as Irish immigrants, which is why there is Dan's Eagle holding the "Olive" and "Arrows" of Joseph their brother (Joseph's secondary emblems), on the American Coat-of-Arms.
* Tradegoods from ancient Carthage have been found in various locations in North America, as recorded in a book written by an eminent Harvard University professor called Barry Fell.
The four tribal standards previously mentioned as being on the pages of the famous Book of Kells are also mentioned by Christ to his Apostle John in Christ's Apocalypse/Revelation.
Revelation/Apocalypse 4:6 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.
4:7 And the first beast [was] like a LION (Judah), and the second beast like a CALF (Ephraim), and the third beast had a face as a MAN (Reuben), and the fourth beast [was] like a flying EAGLE (Dan).
4:8 And the four beasts had each of them six wings about [him]; (three tribes - each tribe with two wings) 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.
4:9 And WHEN those (four) beasts (12 tribes) give glory and honour and thanks to Him that sat on the Throne, Who liveth for ever and ever,
4:10 The four and twenty elders (the Prophets) fall down before Him that sat on the Throne, and worship Him that liveth for ever and ever, and cast THEIR crowns before the Throne, saying,
4:11 Thou art worthy, O Lord, to receive glory and honour and power: for Thou hast created all things, and for Thy pleasure they are and were created.
Jesus told his disciples and the writers of the four Gospels:- Matthew; Mark; Luke and John to go to the "lost" sheep of the "House of Israel", the Ten "Lost" Tribes scattered abroad and to make disciples of all nations. James the Lord's brother later wrote to all twelve tribes*; after the final dispersion of the remnant of the remaining two tribes by the Romans; in his letter in the New Testament. The four emblems represent the tribes of Israel to whom the Gospels were to be preached and that is why they are, quite rightly, on the pages of the "Book of Kells", in Ireland, because the Irish are Israelites, as I have previously explained.
* James 1:1 James, a servant of God and of the Lord Christ Jesus, to the twelve tribes (of Israel) which are scattered abroad: Greetings.