If we should stumble when musicians play,
Time will say nothing but I told you so.
There are no fortunes to be told, although,
Because I love you more than I can say,
If I could tell you I would let you know.
The winds must come from somewhere when they blow,
There must be reasons why the leaves decay;
Time will say nothing but I told you so.
Perhaps the roses really want to grow,
The vision seriously intends to stay;
If I could tell you I would let you know.
Suppose the lions all get up and go,
And all the brooks and soldiers run away;
Will Time say nothing but I told you so?
If I could tell you I would let you know.
For soldiers to run away from battle is what is viewed as cowardice. There also seems to be a bit of word-play going on here: soldiers run, and so do brooks. Running water is a classic symbol for Time, and this would  not be the first time Auden used it like that . This means that cowardice runs as does Time.
If I Could Tell You