Prime numbers have influenced many artists and writers. The French composer Olivier Messiaen used prime numbers to create ametrical music through „natural phenom-ena”. In works such as La Nativité du Seigneur (1935) and Quatre études de rhythm (1949–50), he simultaneously employs motifs with lengths given by different prime numbers to create unpredictable rhythms: the primes 41, 43, 47 and 53 appear in the third étude, „Neumes rythmiques”. According to Messiaen this way of composing was „inspired by the movements of nature, movements of free and unequal durations”. In his science fiction novel Contact, scientist Carl Sagan suggested that prime factorization could be used as a means of establishing two-dimensional image planes in communications with aliens, an idea that he had first developed informally with American astronomer Frank Drake in 1975.