There are, in a way, non-material "things" that exist. For example: information. Think of a novel. It can exist as ink on paper, as a pattern of magnetic charges on a floppy disk that has to be read by a computer or by light reflecting bumbs on a CD that also needs to be read by a computer. Every version of the novel "War of the Worlds" is that same novel and they all have a material existance but we're not talking about a material thing when we talk about a specific novel. We're talking about an information pattern.