We go to a food market with one of two objects in view: Either to buy what we have already decided to cook or to choose what, on that day, might be most desirable to cook. For convenience’s sake, the first purpose can be satisfied by a good supermarket whose food department, reliably stocked with standard items, we use the way we would a hardware store. It has what we want and we want what it has. On the other hand, when we browse the stalls of an Italian street market, such as the great fish and produce market at Rialto, in Venice, we may not know what we are looking for until we see it, but it will have to be something we won’t be able to resist taking home to cook.