The author states his thesis as follows: 'the easy assumption of quantitative variables as the only ultimate explanation of every variation in behaviour is one of the seductive fallacies to which all psychological theorizing is prone.' There is a human need to want to measure and to evaluate quantitatively. The many uncontrolled variables in the analytic situation make it impossible to accurately evaluate how much, how intense a particular psychic event is. A quantitative formulation does not relate itself to the interplay of many conflicting forces. The so-called economic formulations are considered the weakest element in current theories of psychological causation.