The _Ricordi_ show that Michelangelo was still buying marbles and visiting Carrara down to the end of February 1518.

His correspondence from Pietra Santa and Serravezza, where he lived when he was opening the Florentine quarries of Monte Altissimo, does not begin, with any certainty, until March 1518.

We have indeed one letter written to Girolamo del Bardella of Porto Venere upon the 6th of August, without date of year.

This was sent from Serravezza, and Milanesi, when he first made use of it, assigned it to 1517.

Gotti, following that indication, asserts that Michelangelo began his operations at Monte Altissimo in July 1517; but Milanesi afterwards changed his opinion, and assigned it to the year 1519.