What is music, anyhow? People have been offering definitions, descriptions, aphorisms, and witticisms for hundreds of years without arriving at any consensus on the question. Here, in chronological order, are a dozen attempts, mainly by non-musicians, to characterize music:   

Music, moody food of us that trade in love. (William Shakespeare, Antony and Cleopatra, c.1606)  
Music, the greatest good that mortals know, And all of heaven we have below.   
     (Joseph Addison, "Song for St. Cecilia's Day," 1694)  
It is the only sensual pleasure without vice. (Dr. Samuel Johnson, remark, 1776)  
Music is the moonlight in the gloomy night of life. (jean Paul Richter, Titan, 1803)  
Music is the universal language of mankind. (Henry Wadsworth Longfellow, Outre-Mer, 1834)  
Music is well said to be the speech of angels. (Thomas Carlyle, Essays: The Opera, 1840)  
The only cheap and unpunished rapture upon earth. (Sydney Smith, letter, 1844)  
Music is love in search of a word. (Sidney Lanier, The Symphony, 1875)  
Cathedrals in sound. (Alfred Bruneau, speech at a statue of Cesar Franck in Paris,1904)  
Music is, first of all, motion; after that emotion. (James Huneker, Old Fogy, 1913)  
Music, n. An art of sound in time which expresses ideas and emotions in significant forms through the elements of rhythm, melody, harmony and color. (The Random House Dictionary of the English Language, 1967)  
I'll play it first and tell you what it is later. (Miles Davis, c.1970)