The choice of auxiliary depends on the "aspect" and also on whether the verb is intransitive or transitive. Except in the aorist, the auxiliary for intransitives is the verb 'to be', while that for transitives is the verb 'to have'. In the Aorist a different pair of auxiliaries is used, one for intransitives and another for transitives. Since neither of the latter is used other than as an auxiliary, and neither has a participle (or other non-finite form) to provide a convenient citation form, we shall simply refer to them as the (intransitive and transitive) aorist auxiliaries.