The unimportant matters, the minor concerns. This term dates back to the ancient Romans, or perhaps even further. Writers have deemed little things either as too trivial to make a difference (Ovid: “Little things affect little minds,” repeated by Disraeli and Oliver Goldsmith, among others) or as being the building blocks of important matters (Browning: “We find great things are made of little things”). A related phrase is the least little thing, meaning the least important matter or occurrence, as in “The least little thing will set her off in a temper tantrum.”