The one thing we know about his mode of operation is, that he brooked no rival near him, mistrusted collaborators, and found it difficult to co-operate even with the drudges whom he hired at monthly wages.
Light is thrown upon these dissensions between Michelangelo and his proposed assistants by a letter which Jacopo Sansovino wrote to him at Carrara, on the 30th of June 1517.

He betrays his animus at the commencement by praising Baccio Bandinelli, to mention whom in the same breath with Buonarroti was an insult.

Then he proceeds: "The Pope, the Cardinal, and Jacopo Salviati are men who when they say yes, it is a written contract, inasmuch as they are true to their word, and not what you pretend them to be.

You measure them with your own rod; for neither contracts nor plighted troth avail with you, who are always saying nay and yea, according as you think it profitable.

I must inform you, too, that the Pope promised me the sculptures, and so did Salviati; and they are men who will maintain me in my right to them.