In this short series, I will highlight seven foes and seven friends of system safety, both for explanation and intervention. Each is a concept, meme, or device used in thinking, language, and intervention (reinforced by more fundamental foes that act as barriers to thinking).  They are not the only foes or friends, of course, but they are significant ones that either crop up regularly in discussions and writings about safety, or else – in the case of friends – should do.