In keeping with much of the Bible's source material, the image in the Book called Daniel is a watered down version of an old piece of Greek literature from the eighth century BCE. It is first found in a work by the poet Hesiod in his "Theogony" which means the origins of the gods.
His metal image represents a fabled era of gold supplanted by silver, then inferior bronze etc. It refers to a golden race of a golden age and a decline down to inferior base metals; an exemplar of the the contemporary Greek "myth of the races" that there had been a number of step changes in civilization which had started from a perfect high point.
Socrates, "the father of Western philosophy" refers to Hesiod's account which shows that this meme from literature had survived two and a half centuries already.
The writer of the the Book of Daniel, was not Daniel but whoever he was, he was aware of Hesiod's image and probably learned of it through Socrates or his philosophic offspring, Plato or Aristotle. All three of whom make mention of it. The unnamed writer Of Daniel, soon before 167 BCE, certainly employed Hesiod's memorable literary image of the metal colossus, giving Nebuchadnezzar's dream a striking focus. With it, in the manner of a prophet, he was able to tell how he thought things were going to be for immediate future in the second century BCE game of thrones. Clearly with the language and learning of the Classical world at his fingertips he was in a position to manoeuvre his religious readership towards certain directions in Maccabean Judaism.
The prophetic tenor of Daniel has resonated with apocalyptic Christianity especially since 1840 and is responsible for gross "end times" hype and speculation, especially by Adventists and their progeny Jehovah's Witnesses-- none of which has had the scintilla of truth about it.
The book called the Wisdom of Sirach was written around 180 BCE and quotes all of the canonical Jewish texts omitting Daniel, which is one of the many reasons to understand the late dating of Daniel.
