It's like we have many 'blueprints' of our Selves and numerology is one of them. The Chinese believe that the Ear is a blueprint for the rest of your body (the 'little man' in the ear). Palmists read the lines in your hand. Astrology is another (energy that is symbolized by the planets). Reflexology...The list goes on. Macrocosm, Microcosm.
If you think about the number '1'...it brings up the feeling of Individuality. '2' brings up the feeling of having an 'other' to bounce things off of. Relationship number. Number symbolism has been around for a long time...