Meaning of “The course of life is fixed, and nature…”

The verse places change inside a larger rhythm of seasons and purposes, making it useful for thinking about acceptance when one phase of life gives way to another.

Stability is temporary, so practical judgment requires expecting change rather than treating present arrangements as permanent.

Life continues forward despite attachment to what has already happened, so care for the past cannot make the present remain there.

The emphasis is not on controlling every outcome but on meeting what comes with preparedness and acceptance.

Mortality cannot be eliminated, so the practical answer is to make conscious use of the finite span between beginning and end.

Seneca shifts the complaint from life being too brief to attention and time being poorly spent.