Analysis of So we'll go no more a roving

So, we'll go no more a roving
    So late into the night,
Though the heart be still as loving,
    And the moon be still as bright.

For the sword outwears its sheath,
    And the soul wears out the breast,
And the heart must pause to breathe,
    And love itself have rest.

Though the night was made for loving,
    And the day returns too soon,
Yet we'll go no more a roving
    By the light of the moon.