As a youngster growing up, I recall that when I went out with friends, my mom would tell me to make sure that I returned home before it got to be too dark and too late. I’d respond in the affirmative, interpreting her request based on my own preferences and lifestyle: too dark meant I couldn’t see, but there was plenty of light from the streetlights; too late meant before I got too tired and exhausted, but I’m a night owl so that meant that I just needed to return home before 1 a.m.
