Apollonius Dyscolus had made an interesting and linguistically important observation, probably without realizing the full import of his discovery, for the alteration of the temporal reference of an indicative form
seems ordinarily to have the effect of virtualising the action it expresses, whereas with its normal reference it would remain actualised. In the case of wishes expressed by means of the Greek aorist, the reference was switched from past to future, and the consequence was that the essence of the verb was changed from actual to virtual. And this is, in the world of language, only one example of virtualisation by change of temporal reference.