BARTHOLOMAE’S LAW, the name given to a rule of phonetic assimilation in the Indo-Iranian and probably also the proto-Indo-European languages first noted by Christian Bartholomae in 1882. The law is as follows: When a voiced aspirate consonant is followed by a voiceless one, the latter becomes voiced, taking over the former’s aspiration. This is best illustrated from Vedic, in which the aspiration is preserved, e.g., when the morpheme –tá– (as in bhṛ-tá- “carried”) is added to the root dabh- “to betray” (<*dhabh-, see grassmann’s law) the result is *dabh-tá-,which gives dabdhá-; likewise b(h)udh– “to wake” > *budh-tá ­> buddhá-. The Vedic rule can be formulated as *D^hT > DD^h.Bartholomae’s law is also manifested in the Iranian languages, where it explains the development of *ubh-ia- > *ubdha- “woven” (= Ved. ubdhá- “surround­ed,” Skt. -vábhi- “weaving”) > Iranian *ubda- in Young Avestan ubdaēna– “made of woven material,” or *aṷgh-ta “he said” (cf. Gk. eúkhomai) > *aṷgdha > Old Avestan aogədā. It is important to bear in mind that the law covers combinations with –s-; thus *aṷgh-sa “you say” > *aṷgžha > Old Avestan aoγžā; *d(h) ibh-s-(cf. Ved. dabh- “to betray,” dips- “to intend to betray”) > *dhibžh > Old Avestan dißžaidiiai “to deceive, cheat.” Also noteworthy are phonetic changes such as *-dh-t- > *-ddh- > (Ir. *-dd- > Ir. -zd-: e.g., Ved. vṛddhá- “increased” (cf. vardh- = Av. varid- “to multiply”) = Young Avestan vərəzda-; Indo-Iranian *dha-dh-tai “he puts” > *dhaddhaḭ > Old Avestan dazdē (see below); Indo-Iranian *źh-t– > *-`dh-, as in *g(h)ṛźh-ta “he complained” (cf. Av. garəz- = Ved. garh- “to complain” or “reproach”) > *g(h)ṛždha > Old Avestan gərəžda.

In the later Old Iranian languages(Young Aves­tan, Old Persian), however, common morphemes such as the -ta of the participle or the -ta of the 3rd singular of the middle voice (secondary ending) are reintroduced by analogy (almost always in Young Avestan, always in Old Persian; also in Vedic dhatté,for *daddhe, “he puts” against Old Avestan dazdē, see above), e.g., Vedic baddhá– “bound” (from *b(h)adh-tá-) against Young Avestan and Old Persian basta-; Old Avestan aogədā (see above) against Young Avestan aoxta; Vedic dabdhá- (see above) against Young Avestan dapta- “betrayed;” Vedic drugdhá- “harmed” (cf. Ved. drógha- “deceitful,” OPers. drauga- “treason”) against OPers. duruxta- “lied,” etc.

The fact that this phenomenon is found in attested languages as ancient as Old Persian lends weight to the theory that a similar tendency to analogical balancing may be the reason why Bartholomae’s Law generally does not apply in the other Indo-European languages. On the other hand its demonstrable effects on non-Indo-Iranian languages (see Mayrhofer, p. 116) indicate that it was probably operative in proto-Indo-European.