People with blood group 0 Rh – are called “universal donors” and people with blood group AB Rh+ are called “universal receivers.” A common denominator is a number that is a multiple of all the denominators of a set of fractions. It allows you to perform operations with fractions that would otherwise not be possible.
Analogously, think of #selfknowledge as similar to these two concepts. It allows you to give, receive and accomplish things with a much broader range of persons that would otherwise be impossible. When you learn who you truly are and how your mind works your effectiveness, and happiness for that matter, increases dramatically. All things change when you do.