Who First Said 'Knowledge Is Power'?

Francis Bacon (1561-1626) is credited with having coined this phrase in 1597 in a very obscure work called Meditationes Sacrae.
Bacon was many things, he was a lawyer, essayist, scientist and politician.
However, it is likely that we misuse the term today.  What Bacon actually meant by power is reputed to be control of nature, rather than personal or political advantage.
He felt that knowledge could only truly be useful if technology and philosophy were actually unified into one.  He thought that only through studying nature and taking note of natural phenomena could we actually start to understand nature.  From that knowledge we would then be able to control nature and science would be richer for doing this.
However, over the centuries the phrase has come to have a secondary meaning which is that knowledge about someone or something they have done, can give power to s/he who has the knowledge.  

Francis bacon.