Lucretius, De Rerum Natura
William Ellery Leonard, Ed.

Again, all odour, smoke, and heat, and such
Streams out of things diffusedly, because,
Whilst coming from the deeps of body forth
And rising out, along their bending path
They're torn asunder, nor have gateways straight
Wherethrough to mass themselves and struggle abroad.
But contrariwise, when such a tenuous film
Of outside colour is thrown off, there's naught
Can rend it, since 'tis placed along the front
Ready to hand. Lastly those images
Which to our eyes in mirrors do appear,
In water, or in any shining surface,
Must be, since furnished with like look of things,
Fashioned from images of things sent out.
There are, then, tenuous effigies of forms,
Like unto them, which no one can divine
When taken singly, which do yet give back,
When by continued and recurrent discharge
Expelled, a picture from the mirrors' plane.
Nor otherwise, it seems, can they be kept
So well conserved that thus be given back
Figures so like each object.