Takemitsu's sensitivity to instrumental and orchestral timbre can be heard throughout his work, and is often made apparent by the unusual instrumental combinations he specified. This is evident in works such as "November Steps", that combine traditional Japanese instruments, "shakuhachi" and "biwa", with a conventional Western orchestra. It may also be discerned in his works for ensembles that make no use of traditional instruments, for example "Quotation of Dream" (1991), "Archipelago S.", for 21 players (1993), and "Arc I & II" (1963–66/1976). In these works, the more conventional orchestral forces are divided into unconventional "groups". Even where these instrumental combinations were determined by the particular ensemble commissioning the work, "Takemitsu's genius for instrumentation (and genius it was, in my view) ...", in the words of Oliver Knussen, "... creates the illusion that the instrumental restrictions are self-imposed".