This research, a computer-assisted analysis of fifth century drama covering thirty-six plays: eleven of Aristophanes, eighteen of Euripides, and seven of Sophocles, contains detailed information concerning the distribution of letters in their works. 4 A general letter count was refined in terms of vowels and consonants, and the six consonant groups: gutturals, labials, dentals, liquids, aspirates, and sibilants. Each play was examined individually first as a whole and then in part, the trimeter sections, for as a letter or a group is to the whole so should it be to the part. And if not, why not. A principal consideration was the contribution of sibilants as a 'sound*, Sigma was regarded adversely by literary critics in antiquity; this provides a useful link between quantity and quality. With a view to objectivity, the programmed research was designed with few assumptions and the raw data collected without bias. That is, no a-priori assignments of subjective factors such as 'harshness' were made. The frequency of every letter in an initial, medial, or final position within a phonetic-word and within a verse-line was recorded. Each play, and subsequently each author, was described in terms of vowel to consonant ratio, consonant group representation, consonant group position (i, m, or f), and consonant group alliteration in trimeter scenes. Rudimentary 'voice-prints' for each author emerged indicating individual traits, preferences, and time-dependent features of an author's style. Differences between Comedy and Tragedy were measured and the question of Euripides' alleged excessive sigmaticism examined in full. Evidence of Aristophanes' comic characterisation of Euripides was presented in some detail.