If one may judge by the numerous ‘First Latin Courses’ that have appeared in the last twenty years, it is still the belief of many teachers of Latin that if you wish to render in Latin ‘Don't do it’, you may say either Noli facere, or, at the risk of seeming familiar, Ne feceris; but that the corresponding formula, Ne facias, though good enough for the old comedians, is to be avoided entirely, as conveying merely a ‘general’ prohibition—presumably of the type ‘Do not walk on the grass’—and not a ‘particular’ one.