A powerful agent is the right word: it lights the reader's way and makes it plain.
When in doubt tell the truth. It will confound your enemies and astound your friends.
There comes a time in every rightly constructed boy's life when he has a raging desire to go somewhere and dig for hidden treasure.
They did not know it was impossible so they did it
A person with a new idea is a crank until the idea succeeds.
The report of my death was an exaggeration.