What does this quote mean from midsummer nights dream?

Question

lovers and madmen have such seething brains, such shaping fantasies, that apprehend more than cool reason ever comprehends. the lunatic, the lover, and the poet are of imagination all compact. one sees more devils than vast h**l 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 form of things unkown, the poet's pen turns them to shapes and gives to airy nothing a local habitation and a name

Answer 1

Lovers, poets, artists and Madmen don't confine their thoughts and beliefs to reason and logic.  Therefore, many more options, scenarios and possibilities are available to them.

A similar, more recent version of this would be "the fool on the hill" (song by the Beatles)

Day after day, alone on the hill,

The man with the foolish grin is keeping perfectly still.

But nobody wants to know him,

They can see that he's just a fool.

And he never gives an answer .....

But the fool on the hill,

Sees the sun going down.

And the eyes in his head,

See the world spinning around.

Well on his way, his head in a cloud,

The man of a thousand voices, talking perfectly loud.

But nobody ever hears him,

Or the sound he appears to make.

And he never seems to notice .....

But the fool on the hill,

Sees the sun going down.

And the eyes in his head,

See the world spinning around.

And nobody seems to like him,

They can tell what he wants to do.

And he never shows his feelings,

But the fool on the hill,

Sees the sun going down.

And the eyes in his head,

See the world spinning around

Answer 2

lovers and madmen dream dreams  and the poet interprets them

Answer 3

Basically it means that both lovers and madmen create fantasies in their heads of the way things are that may have no basis in reality.  In other works, what  you see in him/her may not be real but just your infatuation.  And poets are just madmen that can make others see their fantasies in their writing.