The year 1908 saw the publication for the first time of Felix Klein’s lectures on elementary mathematics, under the title Elementarmathematik vom Hoheren Standpunkte Aus.17† In this memorable work, Klein expresses himself repeatedly on fundamental questions of mathematics and their relation to mechanics and physics. In this connection, he writes that physics does not need exact mathematics, or Prazisionsmathematik, in itself and can amply get along with an Approximationsmathematik, because the measurement data of physics that underlie any theoretical mathematical treatment are necessarily afflicted by uncertainties—called forth by the inescapable existence of limits on the precision with which measurements can be performed.