Contrary to the standard studio practice of his time, Poussin did not make detailed figure drawings as preparation for painting, and he seems not to have used assistants in the execution of his paintings. He produced few drawings as independent works, aside from the series of drawings illustrating Ovid's Metamorphoses he made early in his career. His drawings, typically in pen and ink wash, include landscapes drawn from nature to be used as references for painting, and composition studies in which he blocked in his figures and their settings. To aid him in formulating his compositions he made miniature wax figures and arranged them in a box that was open on one side like a theatre stage, to serve as models for his composition sketches. Pierre Rosenberg described Poussin as "not a brilliant, elegant, or seductive draughtsman. Far from it. His lack of virtuosity is, however, compensated for by uncompromising rigour: there is never an irrelevant mark or a superfluous line."