How does the poem bring out the elusive nature of happiness in human existence?
The poem is an attempt to distinct happiness and true happiness, the real and imaginary, reality and dream, the pleasure and pain, the ideal and the actual as Richard Fogle calls it. The everlasting and the momentary have been differentiated in the poem. The true pleasure as Keats defines lies not in the physical world which is full of miseries and pain and loss. We chase the beauty and happiness the way the poet chases the bird's song and still at a point the spell is bound to break like a bubble bursts and the human is thrown into the reality to realise the ultimate and inevitable, the death! Happiness is elusive and evanescent and can not be held for ever. It is fickle and promiscuous. The poet when felt that he has found the true happiness in the singing of the nightingale, which is beyond age and time; he wakes up to the reality. He realises that it was just a vision a dream, so is happiness, like a dream, not stationary! All that we can do is delay the inevitability of death through this beauty that gives transcendental happiness.