'Dasein' is an ontological conversion tool, a clever, well-known, sly old South German, peasant-type philosophical fairground wheeze, (cognitivly redolent of the:'Three-Cup-Swap.')

There's a sucker born every minute especially for the cunning gerundial phrase 'BEING THERE', which substitutes the investigative protagonist (the reader or addressee,) in the metaphysical fantasy into a modal locum tenens, or a 'word-stunned,' existentialist jack-o'-lantern, or 'enthused schlemiel' or plain old fall guy.

Watched intently by the little crowd, the young hustler Heidegger places the ball under one of the cups then switches them around with such speed and bewildering dexterity that the onlookers soon become confused and uncertain about which gerundial cup conceals the entitic ball.

Eventually the gawping rustics are convinced that the 'being there' of the ball IS the ball.