Theory = speculation / contemplation, hypothesis

 set of statements or principles devised to explain a group of facts or phenomena 

1. Theory as opposed to practice. "a fine musician who had never studied theory."
2. Abstract reasoning; speculation.

A doctrine, or scheme of things, which terminates in speculation or contemplation,

without a view to practice; hypothesis; speculation. "the theory of music"

"KNOWLEDGE IS POWER" FRANCIS BACON

He emphasizes the importance of empirical evidence and observation 

or experience rather than theory!