One of Bilivert's last major projects was his work in the Cappella Bonsi in the Theatine Church of San Gaetano, Florence. First contracted in 1632, Bilivert completed the painting in 1636 or 1637 for which the Raclin Murphy Snite drawing is preparatory...The subject of the drawing has often been mistaken as the Discovery of the True Cross. This high point of the narrative, however, is found in Matteo Rosselli's altarpiece in the Bonsi Chapel, which depicts St. Helena's interaction with the rediscovered True Cross and her exaltation and adoration of the relic. The figures in Bilvert's drawing and oil painting represent a different aspect of the narrative, that is, the moments immediately before the finding of the Cross in which the saint supervises the laboring excavators.

from Coleman, Seminar in Sixteenth and Seventeenth Century: Old Masterworks on Paper (Notre Dame, 2013)