The base ingredient in nearly all flavorful food liquids is water. That’s because foods themselves are mostly water. Meat juices, vegetable and fruit purees are all obviously watery; cream and mayonnaise and the hot egg sauces less obviously so, but they too are built on water. In each of these preparations, water is the continuous phase: the material that bathes all the other components, the material in which all the other components swim. (The only common exceptions are some vinaigrettes and butter and nut butters, in which fat is the continuous phase.) Those other components are the dispersed phase. The task of giving sauces a desirable consistency is a matter of making the continuous, base phase of water seem less watery, more substantial. The way this is done is to add some nonwatery substance— a dispersed phase—to the water. This substance may be particles of plant or animal tissue, or various molecules, or droplets of oil, or even bubbles of air. And how do the added substances make the water seem more substantial? By obstructing the free movement of the water molecules.