The theme of the song itself is nostalgia and longing for times past. The lyrics mourn

the days that are no more.

The song is unabashedly sentimental, meant to evoke emotions of sadness and desire for the past. The harp-playing maiden recalls dead friends—"up from the underworld." She likens days gone by to the sun sinking into the horizon.

The singer also compares the past to "remember'd kisses after death" and calls these memories "Death in Life." She sings that these memories are "wild with all regret."

As the title indicates, these tears are "idle," meaning they do no good—they are merely sentimental yearnings for what is gone and can't be recaptured. No specific person or situation is mentioned: the message of the poem is generalized regret for times past, and it has a clichéd sound.

The context is important to understanding the meaning of the song. While it dwells on what has gone before and sheds tears for a softened and idealized "set piece" yesteryear of lost love and dead friends, Princess Ida herself roundly rejects this kind of backward-looking sentimentality. She says, after the song is done:

Throne after throne, and molten on the waste
Becomes a cloud: for all things serve their time
Toward that great year of equal mights and rights . . .

In other words, the princess is not about to waste time looking back and feeling sorrow for the past. She states that she prefers to look forward to a better future when women will have achieved equality with men.

Scorning the song, the Princess asks for another song, one that looks toward the promise of the future:

Not such as moans about the retrospect,
But deals with the other distance and the hues
Of promise . . .

The frame of the song encourages us to reject the its message of nostalgia, regret, and tears shed for a rosy-hued past. It invites us to take a critical look at the theme of nostalgia and perhaps to critique as well some of the song's cliched motifs, such as likening the past to autumn. At the same time, we are invited into a dialogue on past and future, and we are asked to question whether the princess goes too far in rejecting memories of days gone by.