This quote is usually given to Sir Francis Bacon. The quote itself that Bacon wrote, however, was “for knowledge itself is power”. That’s probably the reason that “for knowledge, too, itself is power” is given to Bacon as well. It’s a Latin phrase, usually written as “Scientia potentia est”. The phrase never appears like that in the writings that we have from Sir Francis Bacon.
Bacon is an English philosopher. He is known for creating the stepping stones for the modern day scientific method that is taught in schools around the globe. His original ideas didn’t stand long in the scientific world, but the idea that one should have some sort of a process to gathering scientific evidence stuck around.