In regard to theory I am referring to learning the language of music. That is, how to read this new language. The notes representing letters and the letters, when put together making phrases with certain punctuation and phrasing. When the language of music is learned you can express any feeling, any emotion that can be experienced. When you learn about beats, rhythm, time signatures, melody, key signatures, phrasing and the myriad other aspects of music you will find that your math skills, among other developmental skills will be enhanced. People do play their respective instruments without knowing how to read music, but would you read a book without knowing the meaning of the words?