The Moon itself does not wax and wane; the Moon is a lifeless ball of rock, unchanging. It is our perspective on the Moon that changes, as the Moon orbits the Earth and the arrangement of the Sun, the Earth and the Moon changes in a monthly cycle. Because we live on the Earth, but the light that illuminates the Moon comes from the Sun, our view of the Moon changes as the Moon orbits the Earth and the side we see is alternately illuminated and dark.
The shadow of the earth on the moon.
It's the earth shadow
wax and wane
rise set wax wane
The moon must wane in order to change from full to third quarter.
The revolving of the earth and the rotating of the moon.
the earth blocks it from the sun
During the time at sea, the sailors saw the moon wax and wane three times.
The moon orbits the Earth every month and as it does so, we see different parts of the moon lit up by the sun, which causes the moon to go through 'phases'.
Wax and wane
Two weeks, and two weeks to wane.