墨經·光學八條
The Mohist Canon: Eight Propositions on Shadows and Mirrors
The later Mohists 後期墨家 (4th–3rd century BCE)
Pre-Qin · c. 4th–3rd century BCE

Cold Library · Open Stacks · S-002044 · https://coldlibrary.com/s/002044
Rights: Classical Chinese text of the Warring States period; public domain everywhere. Checked for Australia, the EU, the UK, mainland China and the United States as of 11 October 2026. Guidance, not legal advice.
Source: Wikisource, https://zh.wikisource.org/wiki/墨子/經說下 (retrieved 2026-10-11)
English translation: Claude (an AI), 2026 · CC0 1.0
Generated 2026-10-14 from https://coldlibrary.com/en/open-stacks/mohist-canon-optics

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經：景不徙，說在改爲。

說：景，光至景亡，若在，盡古息。

經：景二。說在重。

說：景二，光夾。一，光一。光者景也。

經：景到，在午有端與景長，說在端。

說：景，光之人煦若射，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。

經：景迎日，說在摶。

說：景，日之光反燭人，則景在日與人之閒。

經：景之小大，說在杝𦈢遠近。

說：景，木杝景短大，木正景長小，大小於木。則景大於木，非獨小也，遠近。

經：臨鑑而立，景到，多而若少。說在寡區。

說：臨，正鑒景寡，貌能、白黑、遠近、杝正異於光。鑒景當俱，就去亦當俱，俱用北。鑒者之臭，於鑒無所不鑒。景之臭無數，而必過正。景過正，故招。故同處其體俱然。

經：鑑位景二，一小而易，一大而𦈢，說在中之外內。

說：鑒，分鑒：中之內，鑒者近中則所鑒大，景亦大；遠中則所鑒小，景亦小，而必正。起於中，緣正而長其直也。中之外，鑒者近中則所鑒大，景亦大；遠中則所鑒小，景亦小，而必易。合於中，緣正而長其直也。

經：鑑團景一，夭而必𦈢，說在得。

說：鑒，鑒者近則所鑒大，景亦大；亓遠，所鑒小，景亦小，而必正。

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经：景不徙，说在改为。

说：景，光至景亡，若在，尽古息。

经：景二。说在重。

说：景二，光夹。一，光一。光者景也。

经：景到，在午有端与景长，说在端。

说：景，光之人煦若射，下者之人也高，高者之人也下。足蔽下光，故成景于上；首蔽上光，故成景于下。在远近有端与于光，故景库，内也。

经：景迎日，说在抟。

说：景，日之光反烛人，则景在日与人之间。

经：景之小大，说在杝𦈢远近。

说：景，木杝景短大，木正景长小，大小于木。则景大于木，非独小也，远近。

经：临鉴而立，景到，多而若少。说在寡区。

说：临，正鉴景寡，貌能、白黑、远近、杝正异于光。鉴景当俱，就去亦当俱，俱用北。鉴者之臭，于鉴无所不鉴。景之臭无数，而必过正。景过正，故招。故同处其体俱然。

经：鉴位景二，一小而易，一大而𦈢，说在中之外内。

说：鉴，分鉴：中之内，鉴者近中则所鉴大，景亦大；远中则所鉴小，景亦小，而必正。起于中，缘正而长其直也。中之外，鉴者近中则所鉴大，景亦大；远中则所鉴小，景亦小，而必易。合于中，缘正而长其直也。

经：鉴团景一，夭而必𦈢，说在得。

说：鉴，鉴者近则所鉴大，景亦大；亓远，所鉴小，景亦小，而必正。

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English translation by Claude (an AI)

Canon: A shadow does not move. The explanation lies in its being made anew.

Explanation: Shadow. Where the light arrives, the shadow is gone. If the shadow seems to stay, it is because it is ended and renewed without cease.

Canon: Two shadows. The explanation lies in doubling.

Explanation: Two shadows: two lights hold the object between them. One light, one shadow. The shadows answer to the lights.

Canon: The image is inverted. Where the rays cross there is a point, and the image lengthens from it. The explanation lies in the point.

Explanation: Image. The light comes to the person and shines through like an arrow. What is low enters and goes high; what is high enters and goes low. The feet screen off the light from below, so their image is formed above; the head screens off the light from above, so its image is formed below. Whether the object is far or near, there is a point through which the light passes, and so the image is formed within the screened chamber.

Canon: A shadow facing the sun. The explanation lies in the light turning back.

Explanation: Shadow. When the light of the sun is turned back to shine on a person, the shadow falls between the sun and the person.

Canon: The size of a shadow. The explanation lies in slanting or upright, far or near.

Explanation: Shadow. When the post slants, its shadow is short and large; when the post stands upright, its shadow is long and small. If the light is smaller than the post, the shadow is larger than the post. It is not only a question of small and large, but of far and near.

Canon: Standing before a mirror, the image is turned about; there are many, yet they seem few. The explanation lies in the smallness of the area.

Explanation: Before a level mirror the image is single. Its appearance, white or black, far or near, slanting or upright, follows the light. The image and the person who looks belong together: when one approaches, the other approaches; when one withdraws, the other withdraws; each faces the other, back to back. Whatever the person who looks presents, the mirror reflects it all. The images of what is reflected are countless, but each must pass through the true line. Because they pass through the true line, the image is turned about. So it is the same wherever the body stands.

Canon: In a hollow mirror there are two images, one small and inverted, one large and upright. The explanation lies in being outside or inside the centre.

Explanation: Mirror. The divided mirror: inside the centre, when the object is near the centre, what is reflected is large and the image is large; when it is far from the centre, what is reflected is small and the image is small, but it is always upright. It begins from the centre and follows the true line, lengthening it. Outside the centre, when the object is near the centre, what is reflected is large and the image is large; when it is far from the centre, what is reflected is small and the image is small, but it is always inverted. It meets at the centre and follows the true line, lengthening it.

Canon: In a rounded mirror there is one image, diminished and always upright. The explanation lies in what it takes in.

Explanation: Mirror. When the object is near, what is reflected is large and the image is large; when it is far, what is reflected is small and the image is small, but it is always upright.