Why does earth's rotation axis lean toward the sun for only one-half of its orbit?

The earth is inclined to the plane of its orbit by 23.5 degrees. Therefore for half the time in its earth on its orbit, the north pole will be inclined towards the sun. During this period, the pole receives six months of continuous sunshine. In the other half of the revolution around the sun, the north pole is tilted away from the sun hence receives darkness for 6 months.