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 to 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 (1564-1616): A Midsummer Night's Dream, Act v. Sc. 1.