“Light is sweet.

It is pleasant for the eyes

To see the sun.

Even those who live many years,

Should rejoice in them all.

Yet let them remember

That the days of darkness

Will be many.

All that comes is vanity.”

Light is sweet as it provides your eyes with the pleasant sight of the sun. Even those who get to live a happy long life should remember that there will be plenty of long dark days to come. Your long light filled life is mere vanity or useless, because it will come to an end.