Definition.com
Smell is that, more readily than any other channel, by which memories, imagination, old sentiments, and associations are reached.
Definition.com
Smell has an altogether peculiar force, in affecting us through association... a force differing essentially from that of objects addressing the touch, the taste, the sight or the hearing.
Definition.com
Smell is, in fact, but a single composite sense with taste, whose laboratory is the mouth and its chimney the nose.