Does Your Voice Never Fail You in Singing a Song

Does your voice never fail you in singing a song
So false and so spiteful on us who are young?
When, lady, as surely as you are alive
We are seldom inconstant till seventy-five,
And altho' I have question'd a hundred such men,
They never would say why we should be so then.
In another six years I shall know all about it;
But some knowledge is vain, and we do best without it.