In traditional bread bakeries in rural Italy, bread for a new day is started with a bit of unsalted starter taken from yesterday's bread making. The starter is known as "biga", pronounced bee-ga. No new dry, cake or wild yeast is added, just a cup or so of yesterday's biga. Of course, since the concentration of yeast cells is lower than in a packet or more of purchased yeast, the bread takes longer to rise. It simply takes longer for the yeast cells to multiply to the point that enough CO2 is released to raise the bread. But the slow rise contributes to the very well developed, distinctive flavor of these country loaves. Plus you can go away to work or whatever for the day and come back to bake it later on. You can cut the recipe in half easily. Recipe by Geri Guidetti of the Ark Institute.