Oh my I have a baby !! OK maybe my enthusiasm is a bit exaggerated, I still have to bake with the "creature", but my "chef" is showing definite signs of wild yeast life. After the first day the little ball of dough had just dried out. Another 24 hours later and the hard dry skin had, as you can see from the pic, started to crack.
I peeled off the skin and inside was a beautiful, spongy mass full of bubbles (can you see them below?). It did not smell particularly sour, more alcoholic and sort of nutty (maybe the malt).
After taking away all the dried skin and mixing the remaining dough with some more whole-wheat flour and water to get a firm dough, I kneaded till nice and springy under my hands. Now, about 16 hours later, the dough smells quite sour. The "chef" is now become, as the French call it, a "levain". In Italy it is commonly called "lievito madre" or in Neapolitan dialect "crescito".
Tomorrow I'll refresh it the last time and after 6-8 hours mix the dough together and let it rise over night in the fridge. Hopefully Saturday morning I'll be having breakfast with some nice sourdough bread. I have to say I'm quite surprised how easy it seems. PI had been scared off sourdough by stories of molds and impossibly long times for the yeast to develop. Maybe I should just believe I have the right "feeling" with bread... nay, I'm just kidding!