The quote is contained in Sermon #87, Burl, although it may be a different number in some texts. Rather than take it completely out of context, I'm including a few more paragraphs from that Sermon below:
"While I yet stood in my first cause, I had no God and was my own cause: then I wanted nothing and desired nothing, for I was bare being and the knower of myself in the enjoyment of truth. Then I wanted myself and wanted no other thing: what I wanted I was and what I was I wanted, and thus I was free of God and all things.
But when I left my free will behind and received my created being, then I had a God. For before there were creatures, God was not 'God': He was That which He was. But when creatures came into existence and received their created being, then God was not 'God' in Himself - He was 'God' in creatures.
Now we say that God, inasmuch as He is 'God', is not the supreme goal of creatures, for the same lofty status is possessed by the least of creatures in God. And if it were the case that a fly had reason and could intellectually plumb the eternal abysm of God's being out of which it came, we would have to say that God with all that makes Him 'God' would be unable to fulfill and satisfy that fly!
Therefore let us pray to God that we may be free of God that we may gain the truth and enjoy it eternally, there where the highest angel, the fly and the soul are equal, there where I stood and wanted what I was, and was what I wanted."
Steve