Leibniz's account of modality opens the way for him to present a distinctive kind of compatibilist theory of free will. For, according to Leibniz, Caesar's crossing of the Rubicon was a free act insofar as it spontaneously flowed from his own individual nature or was part of his complete concept and insofar as it represented Caesar's choice of what he perceived to be the best option for him at the time. This action was not necessary – and therefore contingent – because its contrary (for example,