A way of understanding the laws which govem the worId of elementary particIes has not been found yet. Present-day theoretical physicists have to be satisfied with compromises which, at the best, promise some success at the expense of generality and unity. U nder these circumstances a critical analysis of the basic concepts of modem quantum theory may be timely and usefuI. It is hoped that the value of such an analysis may be preserved even if, in the near future, new ways of understanding the basis of elementary particIe physics are discovered. In this monograph one specific aspect of this...