The long-established hypothesis that Gothic ái áu still represented the diphthongs [ai au] in the time of Wulfila is expressed in the writings of such scholars as Jellinek, Streitberg, Braune, and Kieckers. In recent years, however, an increasing number of linguists, including Hirt, Marstrander, Wright, and Mossé, have reached the conclusion that Wulfila's ái áu were no longer diphthongs but had become monophthongized to long open [ε: ɔ:] respectively. Still others, e.g. Wrede and Prokosch, agree only that such a monophthongization took place. Wrede assigns it to the post-Wulfilian period, and Prokosch qualifies his acceptance of the theory: ‘I believe that Hirt is right, but the question is largely one of chronology. Shortly before Wulfila's time, Gmc. ai au were still diphthongs in Gothic ... . Shortly after Wulfila, they were monophthongs’.