Mood is a feature of verbs. It indicates the degree of reality or fulfillment or certainty associated with the action or state of the verb in the speaker's or author's mind.

We might say that "Mood is a state of the mind" — the mind of the speaker. Mood does not indicate reality from any other perspective.

Mood is in some ways the clearest grammatical indicator of the human factor in communication and knowledge. There are four degrees of reality — in other words, four moods (though only three are used regularly in the New Testament. These moods are (in order of typical frequency of use):

  1. indicative
  2. subjunctive
  3. imperative
  4. optative.

Mood can be said to express the state of the speaker's mind about the degree fulfillment (or reality) of the action of the sentence. But the speaker could be mistaken or misleading. That would not affect the grammatical mood.