"The aorist (past definite complete tense) refers to a completed action in the past and the speaker was present, was a witness, or experienced the event. The aorist is formed from perfective verbs.
тој, таа, тоа -(ништо)
There are certain phonetic changes that occur in the conjugation of some of the -И group verbs and some -Е group verbs (verbs that end in -че, -де, -се, -зе, -ие) in aorist tense." This collection studies those ones.