On the strength of this Ricordo, it has been assumed that Michelangelo actually began to paint the Sistine on the 10th of May 1508.  That would have been physically and literally impossible.  He was still at Florence, agreeing to rent his house in Borgo Pinti, upon the 18th of March.  Therefore he had no idea of going to Rome at that time.  When he arrived there, negotiations went on, as we have seen, between him and Pope Julius.  One plan for the decoration of the roof was abandoned, and another on a grander scale had to be designed.  To produce working Cartoons for that immense scheme in less than two months would have been beyond the capacities of any human brain and hands.  But there are many indications that the vault was not prepared for painting, and the materials for fresco not accumulated, till a much later date.  For instance, we possess a series of receipts by Piero Rosselli, acknowledging several disbursements for the plastering of the roof between May 11 and July 27.  We learn from one of these that Granacci was in Rome before June 3; and Michelangelo writes for fine blue colours to a certain Fra Jacopo Gesuato at Florence upon the 13th of May.  All is clearly in the air as yet, and on the point of preparation.  Michelangelo’s phrase, “on which I begin work to-day,” will have to be interpreted, therefore, in the widest sense, as implying that he was engaging assistants, getting the architectural foundation ready, and procuring a stock of necessary articles.  The whole summer and autumn must have been spent in taking measurements and expanding the elaborate design to the proper scale of working drawings; and if Michelangelo had toiled alone without his Florentine helpers, it would have been impossible for him to have got through with these preliminary labours in so short a space of time.

Michelangelo’s method in preparing his Cartoons seems to have been the following.  He first made a small-scale sketch of the composition, sometimes including a large variety of figures.  Then he went to the living models, and studied portions of the whole design in careful transcripts from Nature, using black and red chalk, pen, and sometimes bistre.  Among the most admirable of his drawings left to us are several which were clearly executed with a view to one or other of these great Cartoons.  Finally, returning to the first composition, he repeated that, or so much of it as could be transferred to a single sheet, on the exact scale of the intended fresco.  These enlarged drawings were applied to the wet surface of the plaster, and their outlines pricked in with dots to guide the painter in his brush-work.  When we reflect upon the extent of the Sistine vault (it is estimated at more than 10,000 square feet of surface), and the difficulties presented by its curves, lunettes, spandrels, and pendentives; when we remember that this enormous space is alive with 343 figures in every conceivable attitude, some of them twelve feet in height, those seated as prophets and sibyls measuring nearly eighteen feet when upright, all animated with extraordinary vigour, presenting types of the utmost variety and vivid beauty, imagination quails before the intellectual energy which could first conceive a scheme so complex, and then carry it out with mathematical precision in its minutest details.