Courtesy is a double-sided behavior, fully loaded with both positive and negative implication: It is forceful in its commission, and equally so in its absence. We communicate primitive dominance as well as refinement through the details of our behavior, and in this respect courtesy is little different from style of dress or vocal timbre. Allowing a door to close behind you is a message and a sentiment no less than is holding it open for the next person; in both cases you express yourself and your respect for those around you. In this sense, courtesy, or lack of it, is a weapon. That most basic of urban prohibitions, spitting, is a fine example of the conscious and violent absence of courtesy. Much as someone can direct his voice to indicate unmistakably its intended receiver, he can spit on the street and manage to communicate, through the intensity of expectoration and the relish with which it is committed, particular and specific contempt. An act of this kind should not be mistaken for anything other than a conscious gesture of discourtesy, just as expressive, if not more so, as its gentle flip-side. And in fact even positive acts of courtesy can be freighted with negative messages. Courteous behavior directed to three out of four people in a group is expressive not so much of respect for those three who received the benefit of the positive act, but of contempt for that fourth who was ignored. The insult is especially weighty when considered in the context of the group dynamic, where the awareness of the other three people involved maximizes the disrespect, both as it is communicated by the committer and as it is understood by the receiver.