What he learned of practical business as engineer, architect, master of works, and paymaster during these years among the Carrara mountains must have been of vast importance for his future work.

He was preparing himself to organise the fortifications of Florence and the Leonine City, and to crown S.Peter's with the cupola.

Quarrying, as I have said, implied cutting out and rough-hewing blocks exactly of the right dimensions for certain portions of a building or a piece of statuary.

The master was therefore obliged to have his whole plan perfect in his head before he could venture to order marble.

Models, drawings made to scale, careful measurements, were necessary at each successive step.