We believe that this Oneness is necessarily primary. All that exists other than Him is not primary in relationship to Him. There are many references in the Scriptures. This is the fourth Principle, as affirmed by the verse (Deuteronomy 33:27): "God who preceded [all existence] is a refuge..."It's embarassing, but the clear idea in this principle isn't obvious to me without remembering the Ani Ma'amin or Yigdal version of it, that God is the
This principles is also signifigant because the Rambam breaks with Aristotle who believed in eternal matter and the impossibility of creating yesh me'ayin. It's signifigant because the Rambam writes that he was such an Aristotalian (scientist?) that where the Torah contradicts Aristotle (science?) he would be willing to reinterpret his understanding of Torah, that is unless he is intellectually convinced that Aristotle is wrong, and not his reading of Torah. Evidently the Rambam thought it through and juding by the intellectual honesty and independence of the Rambam, he really believed that creation ex nihilo was how it all went down, yo.
The truth is, here I am headed into the drowsy dog days of the ikkarim, creation ex nihilo. This doesn't interest me very much. All I really have to say about it is that eternity of God is difficult for me to wrap myself around, but only because I apparently haven't advanced past when I was six and didn't get how Hashem was always there. Eternal matter is certainly no less difficult, add a pinch of Occam's Razor and "In the beginning" does it for me.