Two is the number which dominates the world in which we live.
Two is the number of bilateral symmetry, which humans loosely posess. Two nostrils, eyes, ears, hemispheres of the brain, arms, legs, lungs, kidneys, testicles or ovaries.
Two is (usually) the number of people involved in procreative sex, the mechanism which perpetuates our species.
Two is the number of bifurcation of species, one of the processes of evolution. One species undergoes a genetic mutation, and then is another species, while the old species remains.
Two is the number of coordinates by which we describe locations on the earth. Longitude and latitude tell us, in spherical coordinates, where we are on the relatively constant radius of the earth's surface.
Two is the number of binary systems. Not only computers, but our classical world view depends on the dualities of Good or Evil, Right or Wrong, On or Off, Win or Lose. Judeo-Christian Religion, classical science, and fascism all depend on a binary world to operate.
Two is the number of duality, of human consciousness, the separation of the self from God and the rest of the universe. Cogito, ergo sum necessitates this dualistic consciousness. If there is the need to identify the self, then there is a tacit acknowledgement of something else.