People lived by the Month (28 days) the season (90-180 days, and the season varied, winter-Summer is the Temperature climates norm but other places it is Wet-Dry seasons, Indian, African and South east Asia and their Monsoon seasons). People also understood the Summer and Winter solstice and Spring and Fall equinox, but found these to be un-useful when it came to planting or moving animals. Clearly dates you could work other dates from not not significant in themselves (i.e. you did not plant on the Spring equinox, but the 1st or 2nd moon after the equinox).
Given this background "magic" number came into use. These numbers were just useful and thus "Magical". 30 days was to close to a lunar month of 28 days, but 40 days indicated something more then a month, but less then a season (Season itself could vary from three months to six months depending on the climate in the area being discussed). A year was understood and measured from Solstice to Solstice OR equinox to equinox (Until the 1700s England used equinox to equinox, while the rest of Europe use Solstice to Solstice). Scotland was using January 1 as the start of its year by 1600, England, Ireland and the British Colonies were using March 2th, till 1752.
http://en.wikipedia.org/wiki/Old_Style_and_New_Style_dates
Countries as close as Europe in the 1600s could NOT agree on a calendar, do NOT expect something better elsewhere. Thus 40 came to mean a period longer then a month but shorter then a season or a year (and given HOW people where counting, "40 days" may mean 2, 3 or more moons).
On top of this you have 40 YEARS. The average time between generations is about 25 years. Some people have kids in their teens years, others in they 30s and 40s, but the average is about 25 years. If you look back at history, 25 or less years, you often see many of the same people, maybe in different positions but they still in positions of power, authority or leadership. On the other hand once you start to get away 30 or more years from an event, you finally get a situation where NONE (or very few) of the present people in power, authority or leadership had any such position of power, authority or leadership. This is often called a "Biblical Generation" for it is the time Moses lead the Israelis out of Egypt. It is noted that NONE of the people of the Exodus are mentioned (except by reference or someone claiming authority from such person) by the time Joshua invaded Canaan.
Thus 40 years is a time period to show the whole leadership has changed and thus adopted as a term of art meaning that you have had a complete change in leadership. It was a good way to show a change in leadership, even if the change took place over a shorter time period. Thus David and Solomon may NOT have ruled 40 years each, but the people in the positions of power, authority or leadership when David took power were NO longer in such positions when David died and Solomon took over, and the people in such positions when Solomon took over were no longer in place when Solomon died (and the breakup of the United Kingdom into Judah and Israel occurred after Solomon died).
On the other hand 40 years did NOT mean everyone who lived at the beginning had died. Those to young to be in a position of power, authority or leadership 40 years before would still be alive and speak of those days of old. 40 years did not mean something so long ago that no one remembers it, for some people who lived during that previous event would still be alive, but often to old to be able to exercise any power, authority or leadership. Good example today would be Nixon, I remember Nixon. I was a teenager then and remember him and the end of the Vietnam War and Watergate. At that time I was NOT in a position of power, authority or leadership for I was a Teenager, but I remember Nixon and Watergate. On the other hand very few of the people in power under Nixon, are still alive and the few that are NOT in position of power, authority or leadership.
These two uses of 40 reinforced each other, both came to mean a long period of time. thus "40 days" or "40 Years" did NOT mean exactly 40 days or 40 years, but a period of time longer then normal. In the case of 40 days shorter then a year, in the case of 40 years, that the people in charge at the beginning were no longer in charge at the end. People would use the term 40 and people hearing it would know it did NOT mean exactly 40 but a long time period, much longer then a moon or year. In the case of 40 years, people are still alive to remember what happened 40 years ago and compare it to what is happening today and it NOT some historical analysts based on what people have been told or read about (such as what happened up to and including WWII is today) but people who actually lived through the event.
Thus 40 years became a good way to show that ongoing events is related to what happened in the recent past based on first hand accounts NOT history. It also means a new set of leaders who had no power when the last event occur (or the event you are dating from). Reagan is becoming a 40 year situation, his election was 35 years ago, but is there anyone in power today in the GOP who was in power under Reagan? We are getting to a time period when that is or will be true. Yes, I lived and remember Reagan (and my Father saying that if he was a millionaire he would kiss Reagan butt under Kaufman's Clock in Downtown Pittsburgh during Rush Hour, he hated Reagan and all Reagan stood for and that is from a man who voted in Nixon in 1968 and 1972 but he was also a dog face infantryman and could not NOT support the troops).
Side note: "Kissing someone's butt under Kaufmann's Clock in Down Town Pittsburgh was a Pittsburgh-ese for during the days of Streetcars that was the busiest intersection in Pittsburgh. If you were going to kiss someone's ass, everyone one would see it and know about it. It generally used sarcastically.
Back to the concept of 40 being a "Magic number". 40 is NOT magical in the sense you can do magic with it, but it is magical for when used properly in times of old the person using it and the people hearing or reading it understood what it meant, not exactly 40 days or 40 years, but something longer than normal and in the case of 40 years a change in who was in charge, nothing more and nothing less.
40 days came to mean something more then a moon, but less then a season or year. The two 40, 40 days and 40 years, reinforced each other in the concept they were NOT exact time period but something longer and more significant. 40 came to be a useful number, with 40 years being more important then 40 days, but the two time period reinforced each other as making 40 something "magical" importance.
= new reply since forum marked as read
me --BAD lastlib!)
