In a documentary interview, Bruce Lee shared his philosophy of how people should live their life. His teaching suggested people to have a formless mind, be flexible to situations. It is because nothing is set for life. Things keep appearing, vanishing and changing everyday. His famous speech is called "Be water"and it used different persuasive techniques such as "repetition" and "imagery sell".
Don’t get set into one form, adapt it and build your own, and let it grow, be like water. Empty your mind, be formless, shapeless — like water. Now you put water in a cup, it becomes the cup; You put water into a bottle it becomes the bottle; You put it in a teapot it becomes the teapot. Water can flow or it can crash. Be water, my friend.
In his speech, he repeated the words 'water' in every sentences. He also kept stressing how important to 'be/like' water throughout his speech. In Campbell and Keller's (2003) study, they showed that people remember things better when they were constantly repeating. Moreover, Bruce Lee's speech directed people to think how shapeless water can be. He did that by asking people to imagine themselves to be water and the shape of it in different scenarios. In Gregory, Cialdini and Carpenter (1982)'s experiment, they sent salespersons door-to-door to sell cable TV subscriptions People who asked to imagine "how cable TV will broader their entertainment" by salespersons were 2.5 times more to subscribe cable TV than people who didn't imagine any scenario.
Campbell, M.C., & Keller, K.L. (2003). Brand familiarity and advertising repetition effects. Journal of Consumer Research, 30, 292-304.
Chambers, Craig G., and Ron Smyth. (1998). Structural parallelism and discourse coherence: A test of Centering Theory. Journal of Memory and Language 39.4 : 593-608.