'A Midsummer Night's Dream'spoken by Theseus:

The lunatic, the lover, and the poet
Are of imagination all compact.
One sees more devils than vast hell can hold -
That is, the madman. The lover, all as frantic,
Sees Helen's beauty in a brow of Egypt.
The poet's eye, in a fine frenzy rolling,
Doth glance from heaven to earth, from earth to heaven;
And, as imagination bodies forth
The forms of things unknown, the poet's pen
Turns them into shapes, and gives to airy nothing
A local habitation and a name.
Such tricks hath strong imagination,
That, if it would but apprehend some joy,
It comprehends some bringer of that joy;
Or in the night, imagining some fear,
How easy is a bush supposed a bear!

William Shakespeare