what does the symbol of the sun "dragging them all back toward the winter" reveal about Gilbert's feelings on time?

Gilbert is talking about the unavoidably of time and doom in this line

Explanation:

Gilbert here says that the sun is "dragging them all back toward the winter"

Here the symbols of sun and winter are important to understand as well as the symbol of dragging.

The sun is a symbol of time as it is the harbinger of the new day and is the way people know that the time is passing.

The winter can also mean desolation and death too as the end of life is considered the winter of life.

Thus Gilbert here is talking about the inevitability of death in the world with this metaphor of time.