An example of the contrast between realis and irrealis moods is seen in the English sentences "He works" and "It is necessary that he work". In the first sentence "works" is a present indicative (realis) form of the verb, and is used to make a direct assertion about the real world. In the second sentence "work" is in the subjunctive mood, which is an irrealis mood – here "that he work" does not necessarily express a fact about the real world (he could be rejecting necessity and refusing to work), but refers to what would be a desirable state of affairs.