Roman bread.
(printerversion click here for the introduction and illustrations)

The bread in this recipe I have composed from the description  by Faas of several Roman kinds of bread (P.C.P. Faas, Around the table of the Romans: Food and feasting in ancient Rome (Palgrave McMillan 2002). This is not a historical recipe, but an "impressionistic" recipe.

Temper the sourdough with 1 decilitre of the grape juice, 100 gram spelt flour and honey (sponge). Let this stand for at least one to three hours on a warm spot until it has doubled in volume, then mix in the other ingrediënts. Knead well until you have an elastic dough. Let it rise on a warm spot under a damp cloth. If you use extra yeast, one or two hours will suffice, but when sourdough is the only rising-agent, you can also leave it an entire night. When the temperature goes down, rising will be slower. To prevent the dough from drying out, place it in a plastic box with lid, together with some glasses of hot water. You can knead and let rise for a third time, but this is not mandatory. Now you can create your bread in any form you like. Use your fantasy, or create a simple loaf. 
When the bread is formed, let is again rise, this time for half an hour. Preheat the oven to 220ºC/425ºF. Bake the bread for 20 to 25 minutes. 

Sourdough: What is it.  Sourdough is a mixture of lukewarm water and flour (wheat or rye), in which "wild" yeast cultures grow. The mixture (water to flour 1:1 to 2:1) stands for a couple of days at room temperature. The bacteries multiply and cause the caracteristic sour smell. These days often "tame" yeast is also added to the bread dough to help the rising along.
How to make your own sourdough. When you want to make your own dough you have a small problem: how do you catch wild yeast?
You can set the flour/water mixture someplace and hope for a satisfying result. One is dependent on what is in the air. Sometimes you get lucky and a great sourdough is the result, sometimes you get something rather unsavoury, and sometimes nothing happens. Start with 100 gram whole wheat flour and 1 to 2 decilitre lukewarm water. Let it stand at room temperature for a couple of days, covered with a damp cloth. Stir well twice a day. When you have caught the right yeast, the mixture will start to smell sour. After three days add 1 tablespoon flour and 1 tablespoon water, repeat this the next day. In less then a week you have a sourdough ready to bake bread with. When you want to, you can add a teaspoon of honey or sugar.
How to get ready made sourdough. When you want to be on the safe side you can ask a gift of sourdough from a friend that has a good one, or buy a "sourdough starter" and follow the directions on the package.
How to keep your sourdough. Once you have satisfying sourdough you have to take care of it. Keep your little "pets" in the refrigerator in a closed container. Some advice to punch some holes in the cover, but you then risk a rather smelly refrigerator. At least once a week (twice is better) you have to air the sourdough: let it stand, covered with a damp cloth, at roomtemperature for 24 hours. When you look at your sourdough you will see that it has seperated in sediment at the bottom and a grey-brown fluid on top. Stir this well. You will have to feed your pets: after stirring, add equal measures of lukewarm water and flour. Take some of the sourdough out to bake a bread with, or to give away.
How to bake sourdough bread. For  500 gram flour (whole wheat, optionally mixed with rye, oats, millet) use 100 gram sourdough and 3,5 to 4 decilitre water (start with 3,5 decilitre, add more water only if the dough needs it). The recipe for Roman bread has different proportions. You also have the right to experiment!