Every week, on Friday afternoon, towards the end of the workweek, I get a subliminal message reminding me to wish a good friend a "Good Sabbath" - a "Shabbat Shalom" - in anticipation of the imminent arrival of sundown. We exchange the greeting, whether in a text message, voice call or, on rare occasion, in a face-to-face exchange, and whether initiated by him or by me.

The gesture is many things: A marker in my week. A nod to tradition. An homage to a good friend. A pause. An acknowledgment of the cycle of time and nature and its comforting rhythm. A little touch of humanity.