Shelley was admiring the “profuse strains” of the “blithe spirit” and when he compares human songs with the skylark’s
Waking or asleep,
Thou of death must deem
Things more true and deep
Than we mortals dream,
Or how could thy notes flow in such a crystal stream?
He was of strong view that Skylark’s song was much better than any poet’s song ever, and not only this, humans are quite unable to sing like that. After few line he says
Our sweetest songs are those that tell of saddest thought.
The above line is a kind of contradiction. This very song is one of the sweetest but it doesn’t tell of saddest thought. Some may argue that sadness is implicit in it as Shelley asserts that poets cannot produce a song of that much joyousness fraught in it. Was this contradiction deliberate?