from "The Art of Lying"

Oscar Wilde.

...Champing his gilded oats, the Hippogriff will stand in our
stalls, and over our heads will float the Blue Bird singing of
beautiful and impossible things, of things that are lovely and that
never happen, of things that are not and that should be...

For the complete text, see 

http://www.online-literature.com/wilde/1307/

Thanks to Patricia Duindam