On the nature of things (books 1 - 3)   

And to take on the vital motions there.
But think not, haply, living forms alone
Are bound by these laws: they distinguished all.

For just as all things of creation are,
In their whole nature, each to each unlike,
So must their atoms be in shape unlike-
Not since few only are fashioned of like form,
But since they all, as general rule, are not
The same as all. Nay, here in these our verses,
Elements many, common to many words,
Thou seest, though yet 'tis needful to confess
The words and verses differ, each from each,
Compounded out of different elements-
Not since few only, as common letters, run
Through all the words, or no two words are made,
One and the other, from all like elements,
But since they all, as general rule, are not
The same as all. Thus, too, in other things,
Whilst many germs common to many things
There are, yet they, combined among themselves,
Can form new who to others quite unlike.
Thus fairly one may say that humankind,
The grains, the gladsome trees, are all made up
Of different atoms. Further, since the seeds
Are different, difference must there also be
In intervening spaces, thoroughfares,
Connections, weights, blows, clashings, motions, all
Which not alone distinguish living forms,
But sunder earth's whole ocean from the lands,
And hold all heaven from the lands away.

ABSENCE OF SECONDARY QUALITIES

Now come, this wisdom by my sweet toil sought
Look thou perceive, lest haply thou shouldst guess
That the white objects shining to thine eyes
Are gendered of white atoms, or the black
Of a black seed; or yet believe that aught
That's steeped in any hue should take its dye
From bits of matter tinct with hue the same.
For matter's bodies own no hue the least-
Or like to objects or, again, unlike.
But, if percase it seem to thee that mind
Itself can dart no influence of its own
Into these bodies, wide thou wand'rest off.
For since the blind-born, who have ne'er surveyed
The light of sun, yet recognise by touch
Things that from birth had ne'er a hue for them,
'Tis thine to know that bodies can be brought
No less unto the ken of our minds too,
Though yet those bodies with no dye be smeared.
Again, ourselves whatever in the dark
We touch, the same we do not find to be
Tinctured with any colour.
Now that here
I win the argument, I next will teach

Now, every colour changes, none except,
And every...
Which the primordials ought nowise to do.
Since an immutable somewhat must remain,
Lest all things utterly be brought to naught.
For change of anything from out its bounds