of his genius of material.  Nobody left more “unfinished” work than Michael Angelo.  The Victory, the bust of Brutus, the Madonna and Child,[60] to mention a few out of many, show clearly what his system was.  In the statue of Victory we see the three stages of development or completion.  The statue is in the stone, grows out of it.  The marble seems to be as soft as soap, and Michael Angelo simply peels off successive strata, apparently extracting a statue without the smallest effort.  The three grades are respectively shown in the rough-hewn head of the crouching figure, then in the head of the triumphant youth above him, finally in his completed torso.  But each stage is finished relatively.  Completion is relative to distance; the Brutus is finished or unfinished according to our standpoint, physical or aesthetic.  Moreover, the treatment is not partial or piecemeal; the statue was in the marble from the beginning, and is an entity from its initial stage:  in many ways each stage is equally fine.  The paradox of Michael Angelo’s technique is that his abozzo is really a finished study.  The Victory also shows how the deep folds of drapery are bored preparatory to being carved, in order that the chisel might meet less resistance in the narrow spaces; this is also the case in the Martelli David.  As a technical adjunct boring was very useful, but only as a process.  When employed as a mechanical device to represent the hair of the head, we get the Roman Empress disguised as a sponge or a honeycomb.  These tricks reveal much more than pure technicalities of art.  Gainsborough’s habit of using paint brushes four or five feet long throws a flood of light upon theory and practice alike.  There is, however, another work, possibly by Donatello himself, which gives no insight into anything but technical methods, but which is none the less important.  This is the large Madonna and Child surrounded by angels, belonging to Signor Bardini of Florence.  It is unhappily a complete wreck, five heads, including the Child’s, having been broken away.  It is a relief in stucco, modelled, not cast, and is closely allied with a group of Madonnas to which reference is made hereafter.[61] We can see precisely how this relief was made.  The stucco adheres to a strong canvas, which in its turn is nailed on to a wooden panel.  The background, also much injured, is decorated with mosaic and geometrical patterns of glass, now dim and opaque with age.  The relief must have been of signal merit.  Complete it would have rivalled the polychrome Madonna of the Louvre:  as a fragment it is quite sufficient to prove that the Piot Madonna, in the same museum, is not authentic.  One more trick of the sculptor remains to be noticed.  Vasari and Bocchi say that Donatello, recognising the value of his work, grouped his figures so that the limbs and drapery should offer few protruding angles, in order to minimise the danger of fracture.  It was his insurance against the fragility of the stone: