The mood of Horace's Ode 1.4 is generally hopeful, as a cold and bitter winter gives way to spring.
Now that the ice has melted on the fields, fresh flowers start to bloom and "sprigs of myrtle grace our shining brows." Boats are dragged from storage to the shore as it becomes possible once more to sail. Meanwhile, cows are no longer cooped up in their stalls and can once again graze in the meadows. The earth is starting to wake up from its long winter slumber, and signs of new life are to be found everywhere.
Even so, the mood changes somewhat towards the end of the poem when Horace, addressing Sestius, reminds him of "life's brief compass—that is to say, the inherent shortness of life. Death comes for the pauper and the king alike; there's no escaping it no matter who you are.
And the same goes for Sestius. One day, he too will enter the house of Pluto, the god of death and the underworld. The spring may have just arrived and winter may banished for another few months, but none of this changes the fact that all of us will one day experience the never-ending winter of death.