As our Rabbi was listing these examples and saying that we need to learn to hold conflicting ideas in our heads at the same time, a connection dawned on me: the first thing that they teach you in DBT(Dialectical Behavioral Therapy) is to avoid black and white thinking in order to keep our emotions in line and avoid obsessive thinking patterns. We are taught to stop labeling something as just sad or just happy. We are taught to avoid the words always and never and to take things just for what they are, complicated. And there is nothing more complicated than Judaism. Judaism forces us to hold both the pain and suffering of our people's past as well as the joy for the present and future in our heads.
And maybe that's why Judaism helps me. We are reminded so often (and this is not accidental) that there is good and bad, happy and sad in everything. There is no holiday that includes no remembrance or at least twinge of pain. Most of our holidays revolve around the saying, "they tried to kill us, we won, let's eat." Even leading up to Purim, one of the most joyful holidays of the year, on Shabbat Zahor, we read about the Amalakites, a people who we are both instructed to remember and to drive out from the land, a violent precursor to the joy and partying that is involved with Purim.
Judaism, as well as DBT, teaches us that we must hold happiness and sadness in our hearts simultaneously and be okay with it. We must remember the slavery, but be thankful for the freedom; We must celebrate our Simchas(weddings, birthdays, b'nai mitzvah), but remember that they will not last forever. Our brains are certainly capable of this, even though we don't generally put in the effort needed to do it. We can hold these ideas together in our minds. And we should. It's the healthier thing for everyone.