In his poetry as well as in his life Shelley was indeed 'a beautiful and ineffectual angel', beating in the void his luminous wings in vain

Resolve to find thyself; and to know that he who finds himself, loses his misery

Poetry is at bottom a criticism of life.

Ah, love, let us be true
To one another! for the world, which seems
To lie before us like a land of dreams,
So various, so beautiful, so new,
Hath really neither joy, nor love, nor light,
Nor certitude, nor peace, nor help for pain;
And we are here as on a darkling plain
Swept with confused alarms of struggle and flight,
Where ignorant armies clash by night.

Poetry is simply the most beautiful, impressive, and widely effective mode of saying things

Use your gifts faithfully, and they shall be enlarged; practice what you know, and you shall attain to higher knowledge