Another metaphor that turns up in the sutras refers to “a fault of vision.” It can be found at the end of the Diamond Sutra: “Thus shall you think of all this fleeting world, a fault of vision, a bubble in a stream, a phantasm, a dream.” “Fault of vision” translated literally from the Sanskrit is “flowers in the sky.” This refers to the effect that someone with cataracts sees when looking toward a light source. The cataracts create refractions rather like circular rainbows of color. Looking into the sky there can be a number of these, like “flowers in the sky.” As a metaphor in the sutras it is a way of talking about illusion, or a false perception of things. Stepping on a rope and thinking it’s a snake would be “a fault of vision” or “flowers in the sky.”
When the Chinese translate the phrase “flowers in the sky,” an interesting thing happens. The Chinese words for “sky” and “emptiness” are the same. The Japanese pronunciation for the Chinese version of the phrase “flowers in the sky” is kuge. Ku is “sky” and ge is “flower”, and ku also means “emptiness”. Dogen loves this parallel and really works with it.
In the fascicle called Kuge (Flowers of Emptiness) in the Shobogenzo, he says that the optical illusion of flowers in the sky can be understood in a number of ways. It is a “fault of vision” that clears up when we understand it as such, but it is also a phenomenon that arises because of conditions, a dharma like anything else. The Diamond Sutra points this out in reverse by saying all things are like a fault of vision. But Dogen takes it further. Just as suffering causes us to seek the Dharma, illusion, a form of suffering, causes us to seek enlightenment. It should be appreciated for what it is, the cause of enlightenment itself. Of those who wish to cut off this illusion, he says:
"They think kuge should be abandoned; they fail to realize its deep meaning. Just as Buddhas sow the seed of the Buddhist Way among the people and enlightenment together with practice brings it to fruition i.e., liberation, so does kuge sow the seed of universal emptiness... Unfortunately, most students cannot look behind the phenomenal world".