Music is one of the oldest forms of human expression. From Plato's discourse in the Republic to the totalitarian state in our own times, rulers have known its capacity to appeal to the intellect and to the emotions, and have censored musical compositions to serve the needs of the state. See 2 Dialogues of Plato, Republic, bk. 3, pp. 231, 245–248 (B. Jowett transl., 4th ed. 1953) (“Our poets must sing in another and a nobler strain”); Musical Freedom and Why Dictators Fear It, N.Y. Times, Aug. 23, 1981, section 2, p. 1, col. 5; Soviet
Schizophrenia toward Stravinsky, N.Y. Times, June 26, 1982, section 1, p. 25, col. 2; Symphonic Voice from China Is Heard Again, N.Y. Times, Oct. 11, 1987, section 2, p. 27, col. 1. The Constitution prohibits any like attempts in our own legal order. Music, as a form of expression and communication, is protected under the First Amendment. In the case before us the performances apparently consisted of remarks by speakers, as well as rock music, but the case has been presented as one in which the constitutional challenge is to the city's regulation of the musical aspects of the concert; and, based on the principle we have stated, the city's guideline must meet the demands of the First Amendment. The parties do not appear to dispute that proposition.