Now, as in the Latin and other languages, a yawning fellow is synonymous or equivalent to a negligent and sluggish fellow; this idle custom ought certainly to be avoided; being (as was observed) disagreeable to the sight, offensive to the ear, and contrary also to that natural claim, which every one has to respect. For when we indulge ourselves in this listless behaviour, we not only intimate, that the company we are in, does not greatly please us; but also make a discovery, not very advantageous to ourselves; I mean, that we are of a drowsy, lethargic disposition: which must render us by no means amiable or pleasing, to those with whom we converse.
Giovanni della Casa