It is described in the ancient book Mozi, as the third of "Mozi's eight principles of optics," which describes how light passing through a small hole casts an inverted image.
其中第三條說明：「景光之人照若射，下者之人也高，高者之人也下。足蔽下光，故成景於上，首蔽上光，故成景於下。在遠近，有端與於光，故景庫內也」。