The renga is a collective poetic form which was extremely popular in Japan where it developed between the Heian period (794-1192) and the Moromachi, in the fourteenth and fifteenth centuries. The rules which then governed the joint elaboration of linked poems or kusari-renga has attained great strictness. It was not a question of pure game of chance, or of the whimsies of fanciful dialogue. Each poet participating in the communal writing of the renga restricted himself to linking his contribution to that of the poet who handed over to him and thus lent him his voice. If his predecessor or accomplice had just spoken of spring in a haiku, in referring to the month of January, the poet who carried on the chain had to take up the allusion to January and lead it to its conclusion. The third haiku must introduce an idea, related not only to the month of January, but to the notion of spring. The fourth must, however, Avoid all allusion to the seasons, etc. Everything in the poem - it's diction, the use of homonyms and anagrams - was subject to definite rules... In April 1969 four poets of Europe disappeared underground for a week...To tell the truth, the underworld where the Mexican, Octavio Paz, the Italian, Edoardo Sanguineti, the Englishman, Charles Tomlinson, and the Frenchman, Jacques Roubaud were hidden, was only the basement of a small hotel on the Left Bank in Paris...However, once the fixed time of their "cloistering" had run out, the four western hermits climbed back into daylight with the promised harvest : the first European renga had been born in Paris...(From foreword).