 However, as a scientist Leonardo was more empirical than Alberti, who was a theorist and did not have similar interest in practice.Alberti believed in ideal beauty, but Leonardo filled his notebooks with observations on human proportions, page after page, ending with his famous drawing of the Vitruvian man, a human figure related to a square and a circle.In "On Painting", Alberti uses the expression "We Painters", but as a painter, or sculptor, he was a dilettante.