I don't know when it is that adults forget how to play. Even the signs seems to warn us, "Watch Out, there are kids playing you better be careful..." I know that this is to raise awareness but truly, how often do we actually think about the other side of the equation... what other side you ask? I bet you thought those signs were for you to slow down and pay attention because children are little and unobservant and therefore, could be hurt if you were not warned to be aware right? Yes, I guess that is one way of thinking about it, probably the best one as well afterall, I don't want anyone to mistakenly run over my kids when they chase the rocket they just launched across the street I suppose... No, the other side is a warning as well but, for your benefit not theirs. You see, one should exercise Caution when watching children go about playing unfiltered and unfettered by adults forcing them to conform. They may, afterall, rub off on you and get you thinking grand impossible thoughts. They may dare you to be more serious about playing and tinkering, and daresay, oblivious to those around you while you dig deep into those wonderful unanswerables the universe just puts out there begging for folks to question and try to wrap their noodles around. Playing is serious business folks, and one who chooses that course of business must exercise extreme caution for the mere fact, one never knows when they will discover something that will change the world. Kids know this by the way, it's the adults that have to be shown signs to actually get it.