Two distinct breeds of bread baker mirror this division exactly. Flour, water, salt, and yeast. Because that's all there is, each of these reveals an unexpected depth. Plain white flour, it turns out, isn't all that plain. Become obsessed with bread baking and you become obsessed with water.
Chlorine affects flavor and dampens the activity of yeast.
Distilled water, on the other hand, has a flatness to it. So you bring in jugs of well water from the country or great plastic puncheons of spring water from the grocery store. You give up table salt for the cleaner, sharper taste of the pure stuff, whether panned from the sea in France or mined from a salt cave somewhere in Utah. Most of all, however, you ponder yeast. No other substance in the world is as cool, smooth, dry, and clean-scented.