This paper intends to focus on two aspects: how the Latin grammarians developed the concept of epenthesis, and how we can now give an explanation to this phenomenon. After having gathered the phonological evidence from the tradition of Latin philology, we propose that, in prehistoric Latin, the epenthesis of -t- in the -s.r- cluster, and the epenthesis of -p- in the -m.l- cluster, aimed at solving some problems in syllabification, that is avoiding an illicit syllable onset and an illicit coda-onset sequence, respectively. We then observe that, in classical Latin, the only productive process is the epenthesis of -p- in the -m.s- and -m.t- clusters, which has the function of fulfilling the faithfulness constraint on the inflection of the -m- stems, blocking the m > n assimilation process that later took place in the evolution from Latin to Italian.
