Blacknarwhal, I wondered if perhaps you might go to the Bible itself and check the accuracy of that "something that you read" regarding the fast of the firstborn.
I was reading about the Fast of the Firstborn, part of the Passover celebration, and what I'd read suggested that a Hebrew fast actually only went from sunrise to sunset, and not a full 24 hour run as some had suggested previously.
I'm no expert, but I've just finished the 'Feast of the Firstborn" and there was no fasting involved at all beyond eliminating all yeast/leavening agents from eaten foods..ie eating only unleavened bread which is bread made without yeast. It involves avoiding muffins, or bisquits, or cookies, or even cereals which are made with leavening agents. There are other foods in the grain/starch category which are consumed instead.
The feast begins with a huge Passover celebration involving bible reading, prayers, psalms, songs, ritual memorial foods, and a big dinner! The remaining 7 days is what I meantioned above..a week of avoiding leaven.
The only day I've found so far that involved fasting is Yom Kippur and it IS a FULL 24 hour fast. Some even do a 3 day fast depending on how they view scriptures regarding the moon.
According to G-d's calendar, a day begins at sundown and a day ends at sundown. The ending of the day at sundown begins a new day. Therefore, from sundown to sundown is a full 24 hours.
This Yom Kippur fast, as far as I'm unstanding it, is a FULL fast which means BOTH food and drink. It could seem a 12 hour fast because most people do sleep at night and so they would get up in the morning and not eat that day till after sundown, but some people don't sleep; rather they spend that time in intense prayer. If a person is of the 3 day school, one would have to spend quite a LOT of time in prayer in order to honor it.
I hope that helps a bit. Please, do consult the front of the book for further, first hand information.
I don't mean to knock the Rabbi's regarding their wisdom and interpretation, and instructions, but one has to admit that ALL religions have been contaminated with some 'leaven' and so none are absolutely pure except for the word of Yah as he wrote, and intended it. And one can take it a step further in saying that things do get lost in translations so if one has a grip on the original language, you'll pull some additional stuff from it.
I do hope that helps!
As an American you have the right to not believe in guns. You also have the right to not believe in God. But if someone is trying to break into your home, or wants to harm you, the first thing you will do is pick up the phone and call someone with a gun. The second thing you will do is pray that they get there in time. ~Don Moore