Documents - for sitting on

Documents spew out of Celia's printer all the time - white paper with little tracks on them rather like the markings left by very very small birds only far less interesting. Their use to a cat is to sit on. I learned this pretty quickly as a kitten and I might add that I have left my muddy paw mark on many of Celia's documents.
Why are they useful for sitting on? For one thing the paper is smooth and gets nicely warmed up with feline body heat. Unlike carpets there is no static electricity even if it's not quite as warm as carpet. But mainly documents are useful as a way of catching your human's attention.
As most of you cats reading this will know, humans spent an inordinate amount of time staring at a screen or watching paper come out of the printer. Mildly interesting as it is not unlike something coming out of a hole. I sometimes poke the printer when the paper is coming out and Celia says that Fat Ada (my black and white predecessor) used to sit on the printer in the days when they were big rectangular devices. Usually the printer ground to a halt, suffocated by the sheer weight of cat. Ada was large, very large.
I don't sit on the printer much. It's sort slanted and not very comfortable. I sit on documents. This never fails. Celia looks at me and laughs, or swears sometimes. Then she leans over and picks me up and gives me a cuddle. She can't resist.
It's so easy.