The date on which Michelangelo actually began to paint the fresco is not certain.  Supposing he worked hard all the summer, he might have done so when his Florentine assistants arrived in August; and, assuming that the letter to his father above quoted (Lettere, x.) bears a right date, he must have been in full swing before the end of January 1509.  In that letter he mentions that Jacopo, probably l’Indaco, “the painter whom I brought from Florence, returned a few days ago; and as he complained about me here in Rome, it is likely that he will do so there.  Turn a deaf ear to him; he is a thousandfold in the wrong, and I could say much about his bad behaviour toward me.”  Vasari informs us that these assistants proved of no use; whereupon, he destroyed all they had begun to do, refused to see them, locked himself up in the chapel, and determined to complete the work in solitude.  It seems certain that the painters were sent back to Florence.  Michelangelo had already provided for the possibility of their not being able to co-operate with him; but what the cause of their failure was we can only conjecture.  Trained in the methods of the old Florentine school of fresco-painting, incapable of entering into the spirit of a style so supereminently noble and so astoundingly original as Michelangelo’s, it is probable that they spoiled his designs in their attempts to colour them.  Harford pithily remarks:  “As none of the suitors of Penelope could bend the bow of Ulysses, so one hand alone was capable of wielding the pencil of Buonarroti.”  Still it must not be imagined that Michelangelo ground his own colours, prepared his daily measure of wet plaster, and executed the whole series of frescoes with his own hand.  Condivi and Vasari imply, indeed, that this was the case; but, beside the physical impossibility, the fact remains that certain portions are obviously executed by inferior masters.  Vasari’s anecdotes, moreover, contradict his own assertion regarding Michelangelo’s singlehanded labour.  He speaks about the caution which the master exercised to guard himself against any treason of his workmen in the chapel.  Nevertheless, far the larger part, including all the most important figures, and especially the nudes, belongs to Michelangelo.

These troubles with his assistants illustrate a point upon which I shall have to offer some considerations at a future time.  I allude to Michelangelo’s inaptitude for forming a school of intelligent fellow-workers, for fashioning inferior natures into at least a sympathy with his aims and methods, and finally for living long on good terms with hired subordinates.  All those qualities which the facile and genial Raffaello possessed in such abundance, and which made it possible for that young favourite of heaven and fortune to fill Rome with so much work of mixed merit, were wanting to the stern, exacting, and sensitive Buonarroti.