An ancient Celtic poem

I posted this poem from Word.

I have been in many shapes
I have been a narrow blade of grass
I have been a drop in the air
I have been a shining star
I have been a word in a book
I have been an eagle
I have been a boat on the sea
I have been a string on a harp
I have been enchanted for a year on the foam of the water
There is nothing in which I have not been.

An ancient Celtic poem, The Song of Amergin