If it were true, had through the sun’s eclipse
Been manifested, by transparency
Of light, as through aught rare beside effus’d. 
But this is not.  Therefore remains to see
The other cause:  and if the other fall,
Erroneous so must prove what seem’d to thee. 
If not from side to side this rarity
Pass through, there needs must be a limit, whence
Its contrary no further lets it pass. 
And hence the beam, that from without proceeds,
Must be pour’d back, as colour comes, through glass
Reflected, which behind it lead conceals. 
Now wilt thou say, that there of murkier hue
Than in the other part the ray is shown,
By being thence refracted farther back. 
From this perplexity will free thee soon
Experience, if thereof thou trial make,
The fountain whence your arts derive their streame. 
Three mirrors shalt thou take, and two remove
From thee alike, and more remote the third. 
Betwixt the former pair, shall meet thine eyes;
Then turn’d toward them, cause behind thy back
A light to stand, that on the three shall shine,
And thus reflected come to thee from all. 
Though that beheld most distant do not stretch
A space so ample, yet in brightness thou
Will own it equaling the rest.  But now,
As under snow the ground, if the warm ray
Smites it, remains dismantled of the hue
And cold, that cover’d it before, so thee,
Dismantled in thy mind, I will inform
With light so lively, that the tremulous beam
Shall quiver where it falls.  Within the heaven,
Where peace divine inhabits, circles round
A body, in whose virtue dies the being
Of all that it contains.  The following heaven,
That hath so many lights, this being divides,
Through different essences, from it distinct,
And yet contain’d within it.  The other orbs
Their separate distinctions variously
Dispose, for their own seed and produce apt. 
Thus do these organs of the world proceed,
As thou beholdest now, from step to step,
Their influences from above deriving,
And thence transmitting downwards.  Mark me well,
How through this passage to the truth I ford,
The truth thou lov’st, that thou henceforth alone,
May’st know to keep the shallows, safe, untold. 
     “The virtue and motion of the sacred orbs,
As mallet by the workman’s hand, must needs
By blessed movers be inspir’d.  This heaven,
Made beauteous by so many luminaries,
From the deep spirit, that moves its circling sphere,
Its image takes an impress as a seal: 
And as the soul, that dwells within your dust,
Through members different, yet together form’d,
In different pow’rs resolves itself; e’en so
The intellectual efficacy unfolds
Its goodness multiplied throughout the stars;
On its own unity revolving still. 
Different virtue compact different
Makes with the precious body it enlivens,
With which it knits, as life in you is knit. 
From its original nature full of joy,
The virtue mingled through the body shines,
As joy through pupil of the living eye. 
From hence proceeds, that which from light to light
Seems different, and not from dense or rare. 
This is the formal cause, that generates
Proportion’d to its power, the dusk or clear.”