In his quest for accuracy and rigour eventually leading to his contributions to Calculus, Sir Isaac Newton borrowed terminology from an area of classical mechanics called Kinematics. The terms fluent and fluxion incorporated eventually came to be known as variable and derivative. Each set of terms has its advantages in describing the object in question, highlighting one or another aspect. Fluxion in particular is quite useful in poetically illustrating an ‘instantaneous rate of change,’ and may serve us outside the realm of pure mathematical abstraction to bring attention to such immediate movement at each point in time. So, while the change from a measure to the next, from an idea to the next are changes in fluents, there can be said to exist fluxions in music which describe movements across a separate dimension —that of the inner experience. But such a transposition into the realm of musical description is only metaphorical, if useful to expand perception, and should be taken as a flexible mental aid.