As Christian Cajochen and his colleagues put it in their paper on the matter in Current Biology, we just thought of it after a drink in a local bar one evening at full Moon.
How can the same sum total of solar orbits, lunar phases, terrestrial rotations, or transitions of a cesium-133 atom remain constant, but feel so different in our minds?
Confusingly, this phase is properly named “first quarter” because the Moon is one quarter of the way through its cycle, one quarter of the way through its orbit around the Earth, even though it looks half full.