[1][2][3] Under Hirt's law, a non-initial accent was retracted to a non-ablauting vowel, if it was followed by a consonantal (non-syllabic) laryngeal that closed the preceding syllable.
Hirt's law followed the creation of the distinction between fixed and mobile accentual paradigms in early Balto-Slavic.
The result was a straightforward shifting of the columnar accent one syllable to the left, with the paradigm remaining fixed.
While the secondary dominant syllable was caused by tone assimilation by Indo-European metatony, which is in an additional positional distribution.
Such curves have always been aligned, as a result of which one can see lexicalized variants in the form of doublets and triplets, distributed across dialects:[10][11][12] Borrowing a syllable tone from other cases:[13] Reflexes not related to Hirt's law, but caused by the Indo-European metatony “recessive acute ⇒ metatonic circumflex”:[14][15]