Outside the excellent Michael Ross "The Art of Leverage", the power of leverage is
the main core of last Robert Kiyosaki's book
Rich Dad's Retire Young, Retire Rich: How to Get Rich Quickly and Stay Rich Forever
IMHO, it is the best book in the series since Rich Dad, Poor Dad.

Here are some quotes from it:

"David could beat Goliath because David knew how to use the power of leverage."
"Cash flow is the most important word in the world of money. The second most important word is leverage."
"Leverage is the reason some people become rich and others do not become rich."
"Because leverage is power, some people use it, some abuse it, and others fear it."
"Getting rich begins with words and words are free."
"... do more and more with less and less."

Two other quotes to finish:

"If you want something, be passionate. Passion gives energy to your life. If you
want something you do not have, find out why you love what you want and why you
hate not having what you want. When you combine those two thoughts, you will
find the energy to get off your seat and go get anything you want."

"I have heard many people say, "Money does not make you happy." That statement
has some truth to it. But what money does do is buy me the time to do what I
love and pay other people to do what I hate doing."


Rich Dad's Retire Young, Retire Rich: How to Get Rich Quickly and Stay Rich Forever