A paste of ground wheat and water. Yeasts from the air land on the surface and start to grow and multiply. The yeast consumes the sugars from the wheat, and produces carbon dioxide. Bubbles appear. Bacteria also start to colonise the paste, feeding on other sugars that the yeast does not consume.
This dual colony grows, produces lactic acid, produces carbon dioxide. More flour is added, more water, a dough is made. The proteins in the flour join to make a long protein, which is developed by working the dough. it is stretched away, pulled back, turned. The surface becomes smooth, stretchy, soft. The yeast trapped within the proteins keeps growing, producing carbon dioxide. The bacteria keep growing, keep producing lactic acid. The dough swells, becomes puffy, pillowy. It is moulded, shaped, the surface tightens, dries. The dough is put into the warm oven. The yeast grows faster, the gases expand, the dough stretches. And then, the heat is higher, the yeast dies, the protein sets and stiffens. Moisture in the oven gelatinises the starch, creates a stiff shiny exterior. The starch caramelizes, browns, darkens.
And you have a loaf of bread. Just as the Egyptians would have made, just as the goldminers made in California, just as the French have been making for centuries. And it tastes good too.