Allan Kaprow

Imagine some evening when one has sat talking with friends, how as the conversation became reflective the pace slowed, pauses became longer, and the speakers 'felt' not only heavier but their distances from one another increased proportionately, as though each were surrounded by great areas commensurate with the voyaging of his mind. Time retarded as space extended. Suddenly from out on the street, through the open window of a police car, siren whining, was heard speeding by, its space moving as the source of sound moved from somewhere to the right of the window to somewhere farther to the left. Yet it also came spilling into the slowly spreading vastness of the talkers' space, invading the transformed room, partly shattering it, sliding shockingly in and about its envelope, nearly displacing it. And as in most cases where sirens are only sounded at crowded street corners to warn pedestrians, the police car and its noise at once ceased and the capsule of time and space it had become vanished as abruptly as it made itself felt. Once more the protracted picking of one's way through the extended reaches of mind resumed as the group of friends continued speaking.

Allen Kaprow Assemblage, Environments, & Happenings.
A time long ago when all the current clowns weren't paying attention. R.I.P.