A Third Quarter Square between the Sagittarius Moon and Pisces Sun (18 deg) suggests a crisis of faith. A cause or hope that you've invested meaning in may be up for questioning. What you thought was true is dissolving, and nothing is immediately taking its place.
As you move through the Moon's Waning (darkening) phase, you may have to release what you trusted. Know that you are moving towards the March 17th Pisces New Moon, which will present a new truth that goes beyond what you learned or what you've been teaching. The process will be disorienting, but rather than rushing to find a new piece of wisdom, see what happens as you quietly go with the shift from faithful, to questioning, to disillusioned, and finally to understanding.
Pisces' truths transcend what you've been reading/hearing or what you've convinced yourself is right. Pisces truths just are, and they always encompass something more than you. This can make you feel simultaneously small and free, limitless and insignificant.
But you can't deny what's emerging.