A famous saying of Murata Shuko is 'The moon is at its best when partly hidden by clouds'. Behind this idea is the poet Kenko's 'Tsurezure-gusa' ('Essays in Idleness') in which he says, 'Is it true that flowers are only beautiful when tyey are in full bloom and the moon when it is full?'. This is the aesthetic of the beauty of imperfection and of seeing something in the mind's eye. Behind the formation of chanoyu was the formation of this kind of aesthetic. This aesthetic was born of the tradition of waka and of renga poetry which was popular in the Kamakura and Muromachi periods.
Sen no Rikyu's teacher Takeno Joo whose objective was wabi-cha left these words, 'In renga there are the concepts of "withered" and "chill". Chanoyu should also embody these concepts'. Both Shuko and Joo practiced waka and renga, were familiar with that world and took their aesthetic concepts into chanoyu to create wabi-cha. Especially in the world of renga there are the defining concepts of 'chill' and 'withered', and this is found in the treatise on renga by the disciple of the poet Shotetsu, Shinkei (1406-75). This aesthetic theory was passed on to his disciple Sogi (1421-1502) and then to Sanjonishi Sanetaka who was Joo's teacher.
In this way the aesthetics of waka and renga were inherited by the pioneers of chanoyu, Shuko and Joo. The fact that this condition is often symbolized in chanoyu through waka, is because it has a background of classical arts.
Also, in the Kamakura and Muromachi periods, at the popular renga gatherings, people would gather and practice according to the rules. Incense was probably burned and flowers arranged and there was also chanoyu. In this way the culture of chanoyu was born from the development of the form and manners of such gatherings for the practice of the arts, so that the renga gathering can be said to be the mother of chanoyu.