The subjunctive mood derives from the PIE optative mood.
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The optative mood expresses hopes, wishes or commands and has other uses that may overlap with the subjunctive mood.
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The subjunctive mood derived from the PIE optative mood, and was used to express wishes, desires as well as situations that were not regarded as or known to be real by the speaker.
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Altogether there are 28 verb inflections in the optative mood, complete with active and passive voice, present and perfect, three person forms both in singular and plural and a formal plural form.
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Sanskrit verbs have an indicative, an optative and an imperative mood.
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The optative is sometimes used instead of a conditional mood.