The not altogether apocryphal story of his having once constructed a boat out of a bank-post-bill, and launched it on the lake in Kensington Gardens, deserves to be alluded to in this connexion.
On their return from this river journey, Shelley began the poem of "Alastor", haunting the woodland glades and oak groves of Windsor Forest, and drawing from that noble scenery his inspiration.

It was printed with a few other poems in one volume the next year.

Not only was "Alastor" the first serious poem published by Shelley; but it was also the first of his compositions which revealed the greatness of his genius.

Rarely has blank verse been written with more majesty and music; and while the influence of Milton and Wordsworth may be traced in certain passages, the versification, tremulous with lyrical vibrations, is such as only Shelley could have produced.
"Alastor" is the Greek name for a vengeful daemon, driving its victim into desert places; and Shelley, prompted by Peacock, chose it for the title of a poem which describes the Nemesis of solitary souls.

Apart from its intrinsic merit as a work of art, "Alastor" has great autobiographical value.