because little things stack up like a jenga game...wow great! jenga! (jenga is a block puzzle game, with small rectangular blocks that you set up at the beggining of the game with several tiers of 3 blocks, the first tier blocks go horizontal and the second tier goes vertical, so it creates a '+' shape as you stack it. you repeat this process untill you run out of blocks from the game. Then you start, i dont remember the rules exactly but you move blocks from top/middle/bottom to the top and hope it doesnt tip over)
hypothetically your little things are in a tower of little things that prove to be a lot of little things with a lot of support. but while your life progresses, some of these peices move around. While one little thing can hold a large ammount of little things together, one little thing can take them down just as easily. which can be fixed by rebuilding the jenga tower or in real life, the little things that add up.
make sense?