Taste is not as richly endowed as hearing, which can listen to and compare several sounds at the same time: taste is simple in its action, which is to say that it cannot receive impressions from two flavors at once.
But taste can be double, and even multiple, in succession, so that in a single mouthful a second and sometimes a third sensation can be realized; they fade gradually, and are called aftertaste, perfume, or aroma. It is the same way as, when a basic note is sounded, an attentive ear distinguishes in it one or more series of other consonant tones, whose number has not yet been correctly estimated
Men who eat quickly and without thought do not perceive the taste impressions of this second level, which are the exclusive perquisite of a small number of the chosen few; and it is by means of these impressions that gastronomers can classify, in the order of their excellence, the various substances submitted to their approval.
These fleeting nuances vibrate for a long time in the organ of taste: students of them assume without even realizing it a proper stance for the pronouncement of their verdicts, always with necks stretched and noses twisted up and to the left, as it were to larboard.Excerpt from “The Physiology of Taste” by Jean Anthelme Brillat-Savarin (1755-1826)