According to Wikipedia, the concept of virtuous circles comes from the field of economics:
A virtuous circle and a vicious circle (also referred to as virtuous cycle and vicious cycle) are economic terms. They refer to a complex of events that reinforces itself through a feedback loop. A virtuous circle has favorable results, while a vicious circle has detrimental results. A virtuous circle can transform into a vicious circle if eventual negative feedback is ignored.
One way to talk about how music making can improve over time is to look at how an increase in brain function in one area can help lead to an increase in brain function in another area. In my experience, an example of this is how increases in the depth of proprioception in making a note is tied into hearing deeper subtleties in the note.
In learning the horn, for example, it seems to me that as I increase my ability to create more subtle shades of tone, the more I can hear what those tonal shades are. The proprioceptive part of my brain and the listening part of the brain are making connections and working together. The more I can hear what it is I want, the more I can feel what it's like to create that sound, and visa versa.
I think a big part of helping someone on their path of music making is to help them be mindful of as many of these connections as possible. It's impossible to be fully conscious of all them at the same time, but having an idea that they're there can be very helpful. The challenge of teaching music is having a good awareness of how each individual student is progressing in all the areas of music making and nurturing the various areas in tandem.