kamo no koe the voices of wild ducks
honokani shiroshi are faintly white.
Basho trans. by Peipei Qiu
Commentary: ... as darkness begins to permeate the sea, the faint cry of wild ducks fades into the infinite silence; it deepens the stillness, like a piece of whiteness heightens the darkness of the sea. In this poem, the auditory image, “the voices of wild ducks,” is described with a visual term, “white.” This “transference of the senses” has invited numerous comments. Some readers believe that with “whiteness” Basho really is not describing sound but something else -- the waves, the sea, the vapor over the sea, the color of wild ducks, and so forth. Others maintain that “whiteness” does indeed depict “the voices,” and this deliberate confusion of senses is a superb rhetorical technique ....
-- excerpted from Peipei Qiu, Basho and the Dao: The Zhuangzi and the Transformation of Haikai, p.91
The rhetorical device, synaesthesia ("transference of the senses"), is a familiar element in Japanese poetry, and the method of “conceit” is "derived from the Zhuangzi-style yugen in earlier haikai" (ibid., p. 91). For more information about the effective use of synaesthesia and haiku examples, see my "To the Lighthouse" post,Synaesthesia, and for a brief summary and translation of comments on the haiku by Japanese scholars, see Makoto Ueda, Basho and His Interpreters, pp. 123–124.