Geneza słowiańskiego sufiksu comparatiwu *-ěj-ьš- (pol. -ejsz-)

The aim of the article is to present the history of research on the origin of the complex formative of synthetic comparatives in Slavic. Section 1. deals with the earliest hypotheses, which are only briefly discussed due to the methodological immaturity peculiar to the relevant period, i.e. the 19th century. Section 2. concerns the so-called decasuative (or deadverbial) interpretations, including the most popular one, which is based on reconstructed instrumental forms in *-eh1. Section 3. reports a recent modification of this view: it is suggested that the transfer of the decasuative derivation onto verbal stems in *-eh1- > *-ě-, which are assumed as the ultimate derivational base of Slavic comparatives in *-ě-jьš--, makes the explanation more plausible in terms of chronology and typology.