These events work as memory aids because they happen on a regular basis. Somehow it's comforting to see special days and celebrations come around again. The world is still in order, we think. It's all going to be ok.
If man-made events are comforting, think of the regularity of the turning of the planets. We all enjoyed that fabulous "Super Moon" on Saturday and look forward to two more before the summer is over. We know this is so--we depend on it being so--because of the regular, predictable turning of the earth and moon. Fishermen chart the tides and armies plan their movements based on dependable, observable patterns in nature.
Genesis 1:14 tells us that God made the sun, moon, and stars "for signs and seasons, and for days and years." We also have the promise that "while the earth remains, seedtime and harvest, cold and heat, winter and summer, and day and night shall not cease" (Genesis 8:22). We all expect the sun to rise at a predetermined time tomorrow morning; we are planning on a certain amount of daylight before we close our doors, pull our shades, and lie down again to rest.
It's a simple but profound truth: God is faithful. He says through the prophet Malachi, "I am the LORD; I do not change" (3:6). Jesus, we learn in Hebrews, is "the same yesterday, today, and forever" (13:8). Faithful as the sun to rise and the tides to flow, God will be there when we need him. More reliable even than that amazing USA goalie, Jesus has us in his sight.
I think I will sleep well tonight.