That which has drunk the least.

Oh, you mean among animals? And just to clarify further, are you talking about what you can practically get your hands on or what might be a delicacy in the remotest corners of the globe? Because just about every creature that is consumed has a liver, and it is likely to have gone somewhere.

Most anyone in this country can go into a supermarket and get chicken livers. Most can also find calf's liver and/or beef liver. For anything more exotic, one must generally resort to various ethnic markets (or supermarkets rich in ethnic foods), a butcher shop, or some specialty markets.

There is universal consensus that calves' liver is the mildest and most desirable from among four-footed animals. Lamb's liver is also right up there, but much harder to find. The livers of cows, oxen, sheep, and pigs are darker and stronger, and listed in order of desirability. Obviously youth is as important in the liver world as it is in popular culture. The liver of a suckling pig is far superior to that of a full-grown animal. Freshness is also paramount, as liver develops a stronger flavor as it ages (even frozen).

For mildness, poultry livers as right up there with calf's liver. Chicken, goose, turkey, and duck liver are all delicious, and are listed in order of relative strength, although the differences are slight. Foie gras, or fattened goose liver, has political problems, but is buttery in texture, with a subtle, mild flavor (Escoffier has a charming little recipe for a whole foie gras studded with truffles and sealed in puff pastry, if you have a few spare moments and a dollar or two free).

The livers of certain fish were considered delicacies in earlier times, particularly those of the skate, red mullet, and monkfish, and probably still are to certain people and in certain cultures. Cod was at one time always served with its liver, although the mere mention of cod liver oil still elicits shudders from our seniors. The lobster tomalley, or liver-pancreas combo (a green, soupy goo) is often beloved, but now faces a general prohibition (since the liver acts as a filter, it is too much of a repository for dioxin, mercury, and other environmental pollutants).

The livers of game animals do not necessarily go to waste and deer liver is considered to be excellent (we have not tried it, so are relying on the word of others). We also can't really compare the livers of the woodcock, the hare, wild boar, or any of dozen upon dozens of other animals we have not sampled.

Many livers are soaked for several hours in milk to make them milder when cooked. The less tender beef and pork liver are often braised. In many European traditions, quantities of liver from various animals have been turned into terrines, pâtés, sausages, etc., in the charcuterie and butcher trades. The less desirable the meat, the more likely it is to find its way into commercially produced sausages and other mixed meats, with a lot now going into pet food.

If you are not satisfied with our reluctance to choose a mildness winner between chicken liver and calf liver, you will find many recipes that consider them interchangeable. If you can track down kosher calves' livers – they are lighter in color and flavor than standard livers – you may well have found the mildest liver.