In 1896, William Jennings Bryan declared that, “There are two ideas of government. There are those who believe that if you just legislate to make the well-to-do prosperous, that their prosperity will leak through on those below.
The Democratic idea has been that if you legislate to make the masses prosperous, their prosperity will find its way up and through every class that rests upon it.” Later, Lyndon B. Johnson added, in his brutally blunt style: "Republicans [...] simply don't know how to manage the economy. They're so busy operating the trickle-down theory, giving the richest corporations the biggest break that the whole thing goes to hell in a hand basket."
This economic idea of “trickle-down” dates back to the earlier horse-and-sparrow aphorism: “If you feed the horse enough oats, some will pass through to the road for the sparrows.” In our time, it was formally called “supply side economics.” Ross Perot called it “political voodoo.” Whatever you call it, it has been a dominant political policy priority in many governments and corporations for a long time. But, a metaphor producing an easily-visualized image does not make it an apt model of reality.