This Anaximander fragment is important because it shows a departure from mythological thinking, and the beginning of a more scientific approach. In summary, Anaximander states: Whatever has come into existence, must also pass away with necessity. Anaximander uses terms like "existence" and "necessity", and he states a universal law of contingency. Nothing will last: Is is true to say, then, that there is nothing infinite in this world?

We can find the original text in a text by Simplicius, who comments on Aristotle's Physics(24, 13):

"Ἀναξίμανδρος [...] λέγει δ' αὐτὴν μήτε ὕδωρ μήτε ἄλλο τι τῶν καλουμένων εἶναι στοιχείων, ἀλλ' ἑτέραν τινὰ φύσιν ἄπειρον, ἐξ ἧς ἅπαντας γίνεσθαι τοὺς οὐρανοὺς καὶ τοὺς ἐν αὐτοῖς κόσμους· ἐξ ὧν δὲ ἡ γένεσίς ἐστι τοῖς οὖσι, καὶ τὴν φθορὰν εἰς ταῦτα γίνεσθαι κατὰ τὸ χρεών· διδόναι γὰρ αὐτὰ δίκην καὶ τίσιν ἀλλήλοις τῆς ἀδικίας κατὰ τὴν τοῦ χρόνου τάξιν, ποιητικωτέροις οὕτως ὀνόμασιν αὐτὰ λέγων. δῆλον δὲ ὅτι τὴν εἰς ἄλληλα μεταβολὴν τῶν τεττάρων στοιχείων οὗτος θεασάμενος οὐκ ἠξίωσεν ἕν τι τούτων ὑποκείμενον ποιῆσαι, ἀλλά τι ἄλλο παρὰ ταῦτα· οὗτος δὲ οὐκ ἀλλοιουμένου τοῦ στοιχείου τὴν γένεσιν ποιεῖ, ἀλλ' ἀποκρινομένων τῶν ἐναντίων διὰ τῆς αἰδίου κινήσεως."

Since the ancient Greeks did not use punctuation as we do, it is sometimes hard to distinguish between quotes and surrounding text.

Many philosophers have commented on this text fragment, here are some samples:

Aristotle on Anaximander:

There is no beginning of the infinite, for in that case it would have an end. But it is without beginning and indestructible, as being a sort of first principle; for it is necessary that whatever comes into existence should have an end, and there is a conclusion of all destruction. Wherefore as we say, there is no first principle of this [i.e. the infinite], but it itself seems to be the first principle of all other things and to surround all and to direct all, as they say who think that there are no other causes besides the infinite (such as mind, or friendship), but that it itself is divine; for it is immortal and indestructible, as Anaximandros and most of the physicists say.

(Phys. iii. 4; 203 b 7.)

Thomas Aquinas on Creation:

I answer that, Creation places something in the thing created according to relation only; because what is created, is not made by movement, or by change. For what is made by movement or by change is made from something pre-existing. And this happens, indeed, in the particular productions of some beings, but cannot happen in the production of all being by the universal cause of all beings, which is God. Hence God by creation produces things without movement. Now when movement is removed from action and passion, only relation remains, as was said above (2, ad 2). Hence creation in the creature is only a certain relation to the Creator as to the principle of its being; even as in passion, which implies movement, is implied a relation to the principle of motion.

(Summa Theologica, First Part, Question 45, Article 3)