Bartholomae's law

Bartholomae's law (named after the German Indo-Europeanist Christian Bartholomae) is an early Indo-European (PIE) sound law affecting the Indo-Iranian family. It states that in a cluster of two or more obstruents (stops or the sibilant *s), any one of which is a voiced aspirated stop anywhere in the sequence, the whole cluster becomes voiced and aspirated. Thus to the PIE root *bʰewdʰ- "learn, become aware of" the participle *bʰudʰ-to- "enlightened" loses the aspiration of the first stop (Grassmann's law) and with the application of Bartholomae's law and regular vowel changes gives Sanskrit buddha "enlightened".

In both the Indic and the Iranian subgroups, further developments partially obscured the operation of the law: Thanks to the falling together of plain voiced and voiced aspirated stops in Iranian, Bartholomae's law appears synchronically as progressive voicing assimilation after roots that originally ended in voiced aspirates, for example Old Avestan aogda "he said" from PIE *Hewgʰ-to-. This is not true for roots with plain voiced stops, for example Old Avestan yuxta "yoked" from *yug-to-, where Bartholomae's law does not apply.

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