Brillat-Savarin on the number of the senses

They are at least six -- Sight, which embraces space, and tells us by means of light, of the existence and of the colors of the bodies around us. Hearing, which, by the motions of the air, informs us of the motion of sounding or vibrating bodies. Scent, by means of which we are made aware of the odors bodies possess. Taste, which enables us to distinguish all that has a flavor from that which is insipid. Touch informs us of the consistency and resistance of bodies. The last is genesiac or physical love, which attracts the sexes to each other, and the object of which is the reproduction of the species.

It is astonishing that, almost to the days of Buffon, so important a sense was misunderstood, and was confounded with the touch. Yet the sensation of which it is the seat, has nothing in common with touch; it resides in an apparatus as complete as the mouth or the eyes, and what is singular is that each sex has all that is needed to experience the sensation; it is necessary that the two should be united to reach nature's object. If the TASTE, the object of which is the preservation of the individual, be incontestably a sense, the same title must indubitably by preserved on the organs destined to the preservation of the species.

Let us then assign to the genesiac the sensual place which cannot be refused to it, and let us leave to posterity the assignment of its peculiar rank.

(The Physiology of Taste)