法華經義記 8.88

8.88

問曰：「若爾，何故只詺為觀世音耶？」解釋者言：「但行口業則易，身意兩業行善則難也。且娑婆世界多以音聲為佛事，是故從觀世音受名也。」

Question: "If so, why is he only designated as Avalokiteśvara ('Contemplator of the World's Sounds')?" The commentator explains: "To practice only vocal action is easy, whereas for the two actions of body and mind to practice goodness is difficult. Moreover, in the Sahā world, Buddha-works are mostly conducted by means of sounds. Therefore, he takes his name from contemplating the sounds of the world."