GABRIELS STEP OF VIOLA for Tuba (C or B flat) and Piano was written at Christmas 2011 for a little eight years old boy, who had been studying tuba for one year (level in the french music schools : second year of the first Cycle of instrumental studies).
The reference at the "vielle" or "vielle with a wheel" is been going from the characteristic ostinato of the repeated melody by the tuba, melody which is colorized by the piano's harmonies in a medium or sharp register : the "vielle" was used in the old times by the popular music of the ancient folkloric repertory.
All along the score, the repeated melody gets colourful by harmony either by the dialogue between Tuba and Piano, speaking to each other, or by the changing waves of harmony beside a static melody.