Dan

“However, during the period in which the individual is in the immediate presence of the others, few events may occur which directly provide the others with the conclusive information they will need if they are to direct wisely their own activity. Many crucial facts lie beyond the time and place of interaction or lie concealed within it. For- example, the 'true’ or ’real’ attitudes, beliefs, and emotions of the individual can be ascertained only indirectly, through his avowals or through what appears to be involuntary expressive behaviour. Similarly, if the individual offers the others a product or service, they will often find that during the interaction there will be no time and place immediately available for eating the pudding that the proof can be found in. They will be forced to accept some events as conventional or natural signs of something not directly available to the senses. In Ichheiser’s terms, the individual will have to act so that he intentionally or unintentionally *expresses* himself, and the others will in turn have to be *impressed* in some way by him.”
― Erving Goffman, The Presentation of Self in Everyday Life