At the quarter moons (or half-moons—they are the same thing, as mathematically illogical as that seems) the moon is at a point of tension with the sun. Which means, things are tautly vibrating, ready to swing one way or the other. The first quarter is a make-or-break point with intentions set, or things conceived of at the new moon (either get to it, or abandon it and do something else).
With the full moon, energy culminates and something is brought to fruition (or else frustrations run wild).
The last quarter is a point of release. Release of the energy raised over the high moon time. Release of the successes and failures of the cycle. A time to pull back from the push to GET THINGS DONE, step off the ride, allow the downswing, and release pressure.
This month is the Sun Moon cycle, where the soulful moon is dominated by the expressive sun.