Please note that Mommsen uses the AUC chronology (Ab Urbe Condita), i.e. from the founding of the City of Rome. You can use this reference table to have the B.C. dates
The morning mists fell;
what had been begun in the fresh feeling of the national strength
hardened amidst war, with youthful want of insight into the
difficulty of the undertaking and into the measure of their own
talent, but also with youthful delight in and love to the work,
could not be carried farther now, when on the one hand the dull
sultriness of the approaching revolutionary storm began to fill
the air, and on the other hand the eyes of the more intelligent
were gradually opened to the incomparable glory of Greek poetry and
art and to the very modest artistic endowments of their own nation.
The literature of the sixth century had arisen from the influence
of Greek art on half-cultivated, but excited and susceptible minds.
The increased Greek culture of the seventh called forth a literary
reaction, which destroyed the germs of promise contained in those
simple imitative attempts by the winter-frost of reflection, and rooted
up the wheat and the tares of the older type of literature together.