Phonological rules governing aspiration (dasea) and psilosis: pronouns dropping initial 's' become aspirated; prepositions beginning with vowels are psilosed except certain forms; excess vowels become compensatory to the aspirate; initial upsilon affects psilosis/aspiration before chi; neuter -ος endings and vowels before χ show psilosis; general rules for vowels and aspirates with examples.
Πᾶσα ἀντωνυμία ἀποβαλλομένη τὸ 'σ' δασύνεται, σός ὅς, σοῦ οὗ, σέθεν ἕθεν. Πᾶσα πρόθεσις ἀπὸ φωνήεντος ἀρχομένη ψιλοῦται, πλὴν τῆς ὑπό καὶ ὑπέρ οἷον ἀντί, ἐπί, ἀμφί, ἀπό, ἐν, ἐξ. * Τὰ πλεονάζοντα φωνήεντα ἐν λέξεσι ταῖς ἀπὸ φωνήεντος δασυνομένου ἀρχομέναις μεταληπτικὰ γίνονται τοῦ δασέος πνεύματος οἷον ἥνδανεν ἑήνδανεν, ἕερσα, ἕεδνα, ἑώρων. Τὸ 'υ' πλεονάζον ψιλοῖ τὰ πρὸ αὐτοῦ φωνήεντα, ὅρος οὖρος, ἕκηλος εὔκηλος, ὁδός οὐδός, ἕαδε εὔαδε, ὅλος οὖλος. * Τὰ εἰς 'ος' λήγοντα οὐδέτερα δισύλλαβα ἀρχόμενα ἀπὸ φύσει μακρᾶς ψιλοῦται, αἶσχος, ἦθος, εὖρος, εἶδος. οὕτως οὖν καὶ ἦδος ἀπὸ τοῦ ἡδονή μετασχηματιζόμενον. Πᾶν φωνῆεν πρὸ τοῦ 'χ' ψιλοῦται, ἔχω, ἄχος, ἠχώ. τὸ γὰρ ᾗχι δασύνεται, ὅτι κατ´ ἐπέκτασίν ἐστι τῆς 'χι'. τὸ δὲ 'υ' καθαρὸν ἐν ἀρχῇ λέξεως παρὰ πᾶσιν Ἕλλησι πρὸ τοῦ 'χ' εἶναι ἀπείρηται. καὶ τὸ αἴτιον ἐχυρόν. πᾶν γὰρ φωνῆεν πρὸ τοῦ 'χ' ψιλοῦται καὶ τὸ 'υ' ἐν ἀρχῇ λέξεως δασύνεται, δύο οὖν κανόνων ἀλλήλοις ἀνθισταμένων ἐξέφυγεν τὸ 'υ' πρὸ τοῦ 'χ' καθαρὸν εὑρίσκεσθαι. Τὸ 'ε' καὶ 'ο' πρὸ δασέος ψιλοῦται, ὄφις, ἔθνος, Ἔφεσος. Πᾶν φωνῆεν, πλὴν τοῦ 'υ', ἐπαγομένων δύο δασέων, ἢ δασέος σὺν ἀμεταβόλῳ ψιλοῦται, ἴφθιμος, ἄφνω, ἰχθῦς. σεσημείωται τὸ ἑφθός.
Every pronoun, when it drops the ‘σ’, takes rough breathing: σός ὅς, σοῦ οὗ, σέθεν ἕθεν. Every preposition beginning with a vowel is written with smooth breathing, except ὑπό and ὑπέρ, as for example ἀντί, ἐπί, ἀμφί, ἀπό, ἐν, ἐξ.
The vowels that are added in words beginning with a vowel that has rough breathing become recipients of the rough breathing, as for example ἥνδανεν ἑήνδανεν, ἕερσα, ἕεδνα, ἑώρων. The added ‘υ’ makes the vowels before it smooth: ὅρος οὖρος, ἕκηλος εὔκηλος, ὁδός οὐδός, ἕαδε εὔαδε, ὅλος οὖλος.
Neuter disyllables ending in -ος that begin with a naturally long vowel take smooth breathing: αἶσχος, ἦθος, εὖρος, εἶδος; and so too ἦδος, which is reshaped from ἡδονή. Every vowel before ‘χ’ takes smooth breathing: ἔχω, ἄχος, ἠχώ. For ᾗχι has rough breathing because it is an extended form of χι. But that a pure initial ‘υ’ should occur before ‘χ’ has been denied by all Greeks; and the reason is strong. For every vowel before ‘χ’ takes smooth breathing, and initial ‘υ’ takes rough breathing; therefore, since two rules oppose one another, it has escaped being found that ‘υ’ before ‘χ’ is pure.
‘ε’ and ‘ο’ before a rough-breathed sound take smooth breathing: ὄφις, ἔθνος, Ἔφεσος. Every vowel, except ‘υ’, when two rough-breathed sounds follow, or a rough-breathed sound together with an unchangeable consonant, takes smooth breathing: ἴφθιμος, ἄφνω, ἰχθύς. The form ἑφθός is noted as an exception.