Most Jewish doorways are immediately recognizable as such by the mezuzzah posted on the side of the door frame, tilted so that it leans both in and out. We are commanded to mark our doorposts in this way, and even Jews who are estranged from their heritage often keep this mitzvah.

I’ve always loved the sight of mezuzzot: they are small, yet they can be works of exquisite beauty. They are more than just delicate, gorgeous boxes, though: their real power is inside, in the scroll that contains the Sh’ma, a simple declaration of the unity of G-d. Traditional Jews kiss their fingers to the mezuzzah upon passing through a doorway. I have always found that gesture deeply moving.

I’ve been musing lately about why we keep that reminder of our faith on doorways in particular — why not in the living-room or bedroom, where we are likely to hold our most important conversations? Or above the kitchen sink, where our eyes might turn as we prepare the food that sustains our families, where Shabbat dinner takes shape each week?

What is it about doorways?

I guess each doorway, each change, makes us want to check in with G-d. A doorway can be a passageway that changes us — we come in (excited and scared) to new situations, we depart (in resignation or in hope) from situations that no longer work for us. Sometimes we find our way to new places we didn’t even know we were seeking. As we pass through doorways both literal and figurative, we make a habit of remembering G-d with love, of remembering where we came from and what matters to us the most.

From my childhood Torah, the Rodgers & Hammerstein oeuvre, I learned that, “When G-d closes a door, He opens a window.” And when Jew passes through a door, G-d provides an opportunity to reflect on that moment of passage. Responding with love seems exactly the right thing to do.