When you use energy, the rules are very well defined.  The first and second laws of thermodynamics have been well understood for well over a century, and the third for just over a century, but the subject is still viewed by most as being pretty arcane.  This is a pity, both because these laws are of such importance, and because almost everyone has a fair understanding of the first and second laws, even if they think they don't.  Understanding the implications of the laws is another matter.