Common known constants, beautiful paintings, and words we both know.

His knowledge can only reach her, in terms of what they both already know. I really wish to explain you this, but If I were to do that, I would use words, sometimes in writing and sometimes by speaking. Because words have a specific meaning, and the speaker uses them in a particular sequence/combination, often coupled with some rules, to convey a message. This transfer of messages is communication, and a communication is only successful when both the parties receive what has been sent, with absolute accuracy. So knowledge can only spread via the common known constants. Right now between you and me, it's the words that we both have agreed upon to be the common known constant. And that's why paintings are beautiful.