Considering the extensive technology development efforts devoted to computing and measuring rotating machinery vibration signals, it has always struck the author as ironic that when all that is “said and done” the fundamental question “at what level does vibration become too much?” is still often left with an uncertain answer, or possibly an answer that is disputed. It parallels the health industry’s often changing proclamations on how much of certain “healthy” foods are “enough” and how much of certain “unhealthy” foods are “too much.” At the present time, severity criteria for rotating machinery vibration levels are still most heavily governed by “experience.” Most industrial rotating machines are not mass produced like consumer products. Therefore, it is not economically feasible to base the experience factor in rotating machinery vibration severity criteria on a rich statistical database stemming from controlled test-to-damage or destruction of machines at various levels of “excessive” vibration, to quantify statistically how long it takes the vibration to damage each machine at each tested vibration level.