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There are two kinds of days defined in the first chapter of Genesis. One is a creation day, and the other is an Earth day.
God made a distinct difference between night and day on Earth; so that a day on Earth has never been a 24-hour amalgam of light and dark; rather, a day on Earth is when the Sun is up and, conversely, night on Earth is when the Sun is down.
● Gen 1:4-5 . . God divided the light from the darkness. And God called the light day, and the darkness he called night.
● Gen 1:14 . . And God said, Let there be lights in the firmament of the heaven to divide the day from the night
● Gen 1:16 . .And God made two great lights; the greater light to rule the day, and the lesser light to rule the night.
● Gen 1:17-18 . . And God set them in the firmament of the heaven to give light upon the earth, and to rule over the day and over the night, and to divide the light from the darkness.
The final authority on matters of day and night is the Lord himself. He was actually living in Israel during crucifixion week so he would know better than anyone how to define those two physical conditions. When Jesus was here, days and nights were, at the most, only 12 hours each.
● John 11:9-10 . . Are there not twelve hours in the day? If anyone walks in the day, he does not stumble, because he sees the light of this world. But if anyone walks in the night, he stumbles, because the light is not in him.
This world's light is of course the Sun as per Gen 1:14-18. So then, when Jesus was here; day was when the Sun is up and night was when the Sun is down; meaning of course that the three days and three nights of Matt 12:40 indicate three times when the Sun was up, and three times when the Sun was down; i.e. relative to Christ's crucifixion and resurrection: days began with sunrise and nights began with sundown.
NOTE: Days divided into twelve equal periods of sunlight were regulated by what's known as temporal hours; which vary in length in accordance with the time of year. There are times of the year at Jerusalem's latitude when this world's light consists of less than 12 normal hours of sun, and sometimes more; but when Jesus was here; the official number of hours was always twelve regardless.
I don't exactly know why the Jews of that era divided their days into twelve equal periods of sunlight regardless of the seasons, but I suspect it was just a convenient way to operate the government and conduct civil affairs; including the Temple's activities (e.g. the daily morning and evening sacrifices)
Anyway: it's quite obvious that the Good Friday model is unworkable because it's impossible to fit three physical nights between Friday afternoon and Sunday morning.
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