I ran across the term "Black Fast" and looked it up. The articles I'm finding indicate that it's extreme, and give some information about the types of foods allowed during it, but I keep expecting to find information on when it was performed and why. In my experience, in Catholic tradition, there is a detailed reason and circumstance for just about everything, and I'm just not finding it.
Also, based on the restrictions, this looks to be something that is intended to be something done for an extended period of time, not just a few days...
The details of the fast, as they were prior to the tenth century, are as follows:
- No more than one meal per day was permitted
- Flesh meat, eggs, butter, cheese and milk were forbidden
- The meal was not allowed until after sunset
- Alcohol was forbidden
- During Holy Week, the meal consisted exclusively of bread, salt, herbs, and water
No more than one meal per day would be hard for a few days, but doable, so I have to assume that this fast is meant for extended periods.
The closest I could come to a "how long" answer was a blurb in Wikipedia, but it it about how the Eastern Orthodox Church practices it today.
The Black Fast is still observed by the Eastern Orthodox on Wednesdays and Fridays and during the 40 days of Lent and three other fasting periods of the year.
So, if anyone can fill in the blanks, and explain when it is done, why it is done, and for how long it is done, I'd greatly appreciate it.
