《韩非子·外储说左上》
画竹简的人说； 筑一道十板高的墙，在墙上凿一个八尺大的窗，然后等到太阳刚出来时把竹简放在窗上对着阳光看看。 
画筴者曰： 筑十版之墙，凿八尺之牖，而以日始出时加之其上而观。 
The person who drew the bamboo strips said: Build a ten-foot-high wall, make an eight-foot-wide window in the wall, and wait until the sun just rises to put the bamboo strips in the window and look at them in the sunlight.