The proper meaning of Patet and its overwhelming importance for the mortals.
Patet does not mean forgiveness of the sins. The word Patet is derived from the Avestaic word Paityogat, which means to go against or to check or reward in return, to get prepared to receive coin for coin. Patet hence means a trial to stand against the evils that had befallen, by not committing those evils again,-thus to check a sinful life and at the same time to get prepared to receive coin for coin i.e. to get ready to suffer the punishment of the sin performed. There is nothing of forgiveness in it.
Nay, Patet means an urgent desire with a penitent sincere attitude to be invested with resignatory powers, enabling him to forbear the chastisement of the sins committed, calmly, cheerfully, and ungrudgingly, with a fervent hope for the future i.e. with, heartful prayer to be gifted with Asne-Khered i.e. real consciousness and character to withstand the temptations of the sins appearing again before him. This prayerful attitude is taken as asking for mercy in which the devotee is ready and willing to suffer the punishment for the sins is taken as a mercy as that will lead to umede-ristakhiz i.e. salvation.
(Extract from “Essential Origins of Zoroastrianism” (pg 35-36) – by Late Dr. Framroze S. Chiniwalla.