A Teenage Boy and Girl with a Viewer for an Optique Picture (Nozoki-karakuri); Kōbō Daishi’s Poem on the Jewel River of Kōya… https://www.rawpixel.com/image/9241126/image-paper-art-vintageFree Image from public domain licensePeep-show, Vue d'optique Representat le Pont Marie et le Pont Rouge a Paris, No. 66 https://www.rawpixel.com/image/9065305/image-art-watercolor-vintageFree Image from public domain license