The first of these is a perfective stem, as in Geʿez qabar-a 'he buried'; the Geʿez perfective stem resembles that of the Arabic and the Northwest Semitic languages both in function (past perfective) and in marking the subject by means of a suffix.
Some conjugational paradigms of today's languages (and also of extinct ones such as Egyptian and Semitic Akkadian) derive from this suffix conjugation, including practically all paradigms in Egyptian, the Akkadian stative, the West Semitic perfective, and the qualitative in Kabyle (an Amazigh language).
In the imperfective and perfective aspects there were two sets of endings, distinguishing two voices: active, in which typically the subject was not affected by the action, and mediopassive, in which typically the subject was affected, directly or indirectly.
Thus, the verb 'to find' has the shape af in the aorist paradigm but has the two forms ufi and ufa (depending on the person and number of the subject) in the perfective aspect paradigm.
Roughly, the perfective marker indicates completed, momentary action; its absence signifies an action viewed as incomplete, continuous, or repeated.
The future is expressed by a particle tha (from earlier thé[o] na '[I] want to') followed by a finite verb e.g., tha grápho 'I will write.' Formally, the finite forms of the verb (those with personal endings) consist of a stem + (optionally) the perfective aspect marker (-s- in active, -th- in passive) + personal ending (indicating person, tense, mood, voice).
To mark such forms unambiguously as past indicatives, an augment, usually consisting of the vowel e, could be prefixed e.g., *é-gwhen-t 'he slew,' *é-H1es-t 'he was.' Verbs in the perfective aspect without a mood suffix did not occur with primary endings and thus lacked a true present tense.
In complex sentences, the main verb clause occupies the final position and is preceded by subordinate clauses that end in nonfinite verbs (those that are perfective, durative, conditional, concessive, and so on).
For decades heated debates have focused on the functions and interrelations of the most basic inflectional categories, often discussed in terms of dichotomous subsystems such as "state versus action," "transitive versus intransitive," "punctual versus durative," or "perfective versus imperfective".
According to this terminology, the "present" stem is used for imperfective aspect (ongoing or repeated process), the "perfect" stem for stative aspect (state resulting from the completion of the process), and the aorist stem for perfective aspect (completed process).
