This means he had leisure. He taught, but also pursued his own interests. Remarkable about his Newtonian conversion is not the change of heart, but the change in competence. His first publication, despite its brilliance, reveals his confusions over basic mechanics and a remedial grasp of the mathematics needed to understand Newton. His next group of works displays a firm grasp of celestial mechanics and a growing appreciation of the Principia. Digesting its contents, particularly in the given form (in fluxion instead of normal calculus) could have taken months, if not years.