Two is the first true number in the ancient reckoning, the first multitude, and with it enters everything that one lacks: division, otherness, opposition and relationship. To count to two is to have a self and something else, and from that follows the whole symbolism of the pair, male and female, light and dark, active and passive, the two that may be opposed or joined. Greek thought placed two on the side of the indefinite and the unlimited, the even against the odd, and many traditions treat the doubling of one as a fall from unity into duality, the origin of conflict but also of complement and of love, which needs two.
In modern numerology two is the number of partnership, cooperation, diplomacy, sensitivity and the peacemaker, the self in relation rather than in assertion, the balancing counterpart to the one. As with all the digit meanings, this reading comes from the American numerology of the early twentieth century, the Balliett and Jordan system, and is not inherited from antiquity despite the Pythagorean label attached to it.