Udakacandra

udakacandra (T. chu zla; C. shuǐ yuè 水月 / shuǐ zhōng yuè 水中月). Translated as "reflection of moon in water," "the moon reflected in water," etc.

In the Mahayana tradition, this is a common metaphor for the emptiness (sunyata) of phenomena. The moon appears in the water as a reflection, but it has no reality of its own.

Udakacandra is identified as:

• one of the eight similes of illusion (listed in Tibetan sources)
• one of the ten metaphors for emptiness listed in the Dazhidu lun, chapter 11

According to the Dazhidu lun:

[The assembly of bodhisattvas] accepted that dharmas are like the ‘moon reflected in water’ (udakacandra). Actually, the moon (candra) is situated in space (ākāśa) but its reflection (bimba) appears in the water (udaka). In the same way, ‘the moon’ of the true Dharma (bhūtadharma) is in ‘the space’ of suchness (dharmatā) and the peak of existence (bhūtakoṭi), but its ‘reflection’ — the wrong notions of ‘me’ and ‘mine’ — appear in the ‘water’ of the minds of fools (bālacitta), gods or men. This is why dharmas are like the moon reflected in water (udakacandra).