This paper closely analyzes two types of 'instantaneous' situations in which the non-progressive form of the present tense is frequently used: commentarial and demonstration situations. The use of the non-progressive form may be conditioned by the non-durative nature of the described microevents, by the speaker's perception of his role and by the conventionalized nature of the macroevent itself. These considerations may also apply to other rule-based settings such as stage directions, résumés of plots, chapter headings in novels.