Editing Subjunctive mood (section)

===Proto-Indo-European===
The [[Proto-Indo-European language]], the reconstructed common ancestor of the [[Indo-European languages]], had two closely related moods: the subjunctive and the [[optative mood|optative]]. Many of its daughter languages combined or merged these moods.

In Indo-European, the subjunctive was formed by using the full [[Indo-European ablaut|ablaut]] grade of the root of the verb and appending the [[thematic vowel]] *''-e-'' or *''-o-'' to the root stem, with the full, primary set of personal inflections. The subjunctive was the Indo-European ''irrealis'', used for hypothetical or counterfactual situations.

The optative mood was formed with a suffix *''-ieh<sub>1</sub>'' or *''-ih<sub>1</sub>'' (with a [[laryngeal theory|laryngeal]]). The optative used the [[clitic]] set{{clarify|date=April 2013}} of secondary personal inflections. The optative was used to express wishes or hopes.

Among the Indo-European languages, only [[Albanian language|Albanian]], [[Avestan]], [[Ancient Greek]], and [[Sanskrit]] kept the subjunctive and the optative fully separate and parallel. However, in Sanskrit, use of the subjunctive is found only in the Vedic language of the earliest times, and the optative and [[imperative mood|imperative]] are comparatively less commonly used. In the later language (from c. 500 BC), the subjunctive fell out of use, with the optative or imperative being used instead, or merged with the optative as in Latin. However, the first-person forms of the subjunctive continue to be used, as they are transferred to the imperative, which formerly, like Greek, had no first person forms.