of the nature of things

From Lucretius' De Natura Rerum

Thus too, if all things are create of four,
And all again dissolved into the four,
How can the four be called the primal germs
Of things, more than all things themselves be thought,
By retroversion, primal germs of them?
For ever alternately are both begot,
With interchange of nature and aspect
From immemorial time. But if percase
Thou think'st the frame of fire and earth, the air,
The dew of water can in such wise meet
As not by mingling to resign their nature,
From them for thee no world can be create--
No thing of breath, no stock or stalk of tree:
In the wild congress of this varied heap
Each thing its proper nature will display,
And air will palpably be seen mixed up
With earth together, unquenched heat with water.
But primal germs in bringing things to birth
Must have a latent, unseen quality,
Lest some outstanding alien element
Confuse and minish in the thing create
Its proper being.

heraclitus

Things which are put together are both whole and not whole, brought together and taken apart, in harmony and out of harmony; one thing arises from all things, and all things arise from one thing.

(or alternatively:)

The bones connected by joints are at once a unitary whole and not a unitary whole. To be in agreement is to differ; the concordant is the discordant. From out of all the many particulars comes oneness, and out of oneness come all the many particulars.

-- Fragment 10

This world of beauty and order, the same for all, neither any God nor any man created, but it was ever and is and shall be ever-living Fire, kindled in measures and quenched in measures.

(or alternatively:)

This world-order, the same of all, no god nor man did create, but it ever was and is and will be: everliving fire, kindling in measures and being quenched in measures.

-- Fragment 30.

The way up down one and the same. ( ὁδὸς ἄνω κάτω μία καὶ ὡυτή. )

-- Fragment 60

(the alterative versions are the more technical/direct.)