It's a landmark for a young child to count to 100; it sort of covers all the "ordinary" numbers. One hundred is obviously significant for other groupings: 100 cents is a dollar; 100 yards is a touchdown; 100 years is a century, and the landmark for a very long life. It makes sense, then, that in the Bible, 100 represents fullness or a state of completion, or in some instances simply "much." For instance, people marvel that Abraham had Isaac when he was 100 years old; the number represents the point at which the Lord, when growing up as Jesus, united the human elements of himself with the divine elements and in a sense became "complete.

470. 'The book of the generations' is a record of those who belonged to the Most Ancient Church. This is quite clear from what follows, for from here down to Eber in Chapter 11 the names used nowhere mean actual persons but real things. In most ancient times the human race was divided into houses, families, and nations. A house consisted of husband and wife together with their children, and also other members of their family who were the servants. A family consisted of a number of such houses, many or few, who dwell in close proximity to one another, but not together. A nation consisted of a number of families, many or few.