I traditionally begin a paper with one or more definitions. This is not pedantic but a matter of necessity if one is to communicate efficiently, particularly nowadays when loose terminology and imprecise usage of words is very much in evidence. Ask ten people what they understand by planning, and you will get ten variations on a theme; ask ten people what they mean when they talk about ‘the environment’—which everyone does—and you will find not ten variations on a theme, but ten themes.