"after studying the major odes of keats, it seems that one of the dominant themes in it is the transitoriness or the decay of beauty. for example when he says:
"Fade far away, dissolve, and quite forget
What thou among the leaves hast never known,
The weariness, the fever, and the fret
Here, where men sit and hear each other groan;
Where palsy shakes a few, sad, last gray hairs,
Where youth grows pale, and spectre-thin, and dies;
Where but to think is to be full of sorrow
And leaden-eyed despairs;
Where beauty cannot keep her lustrous eyes,
Or new love pine at them beyond tomorrow".

similar themes are also present in his ode on a grecian urn and to psyche and to fancy..but his another famous poem opens with the lines:
"a thing of beauty is a joy for ever,
its lovely increases it will never pass into nithngness".
so my question is that IS NOT THERE A VERY SHARP CONTRAST BETWEEN THESE TWO APPROACHES, IF YES WHY.. AND IF NOT.. HOW? can any body explain it to me?