With a fine enough scalpel, everything is uniqueMichael Goulder, Luke: A New Paradigm (JSNTSup. 20; Sheffield: Sheffield Academic Press, 1989), 280.
I have been looking for this quotation for ages, and finally came across it today. I had remembered using it myself (e.g. in my review of Kim Paffenroth's Story of Jesus according to L, "In the search for 'un-Lukan' features, one cannot help thinking that with a sharp enough scalpel, everything is unique"), and I had always attributed it to Michael Goulder, but I was beginning to think that I had invented it myself. It turns out that my memory was correct and that it does come in Goulder. It's a nice line. In context, Goulder is criticizing the fine distinctions made by Schürmann on Luke 3.15, "Schürmann denies the verse to Luke by fastidious distinctions . . . "