Explain about the 1307, etc...OK - here maybe I should just paraphrase briefly from the AEONS chapter on the subject:
1. Ussher becomes obsessive about finding the date of human creation (ADAM). It was approximately 1620 or so.
2. Ussher finds a literary agent in London named Thomas Davies. He commissions him to find the best existing old testament manuscripts in their original languages.
3. In 1624 Davies finds for Ussher a partial OT (just the 5 books of Moses) in Samaritan. The following year, he finds another version - this time in Chaldean. He eventually also obtains a Greek and Hebrew version as well.
4. Ussher now faces two problems:
a> The chronology of Genesis for the time from creation to the flood is "floating" - i.e. there is no way to pin it to a modern calender (i.e. to the year AD 1) without finding something in secular history which can lock into a matching dated event.
b> The four biblical manuscripts had different time measurement schemes and dates for the time from the creation to the flood - the Samaritan worked out to 1307 calender years, the Hebrew and Chaldean to 1656 years, and the Greek to 2242. Ussher took the 1656 mainly because there were two references to this number.
5. Now Ussher works on the floating chronology problem for 24!! years: Finally he makes a discovery in the 2 Kings 25 verse 7:
"and it came to pass in the seven and thirtieth year of the captivity of Jehoiachin king of Juday, in the twelfth month, on the seven and twentieth day of the month, that Evil-merodach king of Babylon in the year he began to reign..."
This was enough to link the OT chronology to the kings of Babylon: 2nd century astronomer Ptolemy linked Nebuchadnezzar to Greek history. The reasoning was that Evil-merodach must have started to reign when Nebuchadnezzar died. Now he could hook up the existing Julian calender to death of Nebuchadnezzar and make it 562 BC. Now he could add up all the prophets and kings, etc. and come up with the famous date 4004 BC for creation itself.
And, as I was posting before, I am amazed at the honest intellectual effort this guy Ussher put into this work - way more than the stuff that Russel and later the WT dreamed up (based a lot on Ussher and others). Still, though a real look at how this date came about shows how fuzzy this kind of chronology really is - we don't really even know the date of Jesus birth - let alone exact numbers for all the rest of this string of chronology. (I.E. all the variance in the time creation>>flood). Real historians know this and don't insist on silly arbitrary dates.
But now poor old Ussher has a lapse of reasoning, spending the last of his time on earth speculating up the month, day, and even hour of the exact day one of creation - 6 pm Saturday 22 October 4004 BC. This last (and maybe some of the first part) was all a figment of imagination.
James