Apparently, it was a crime in ancient Rome to "use magic to move crops." (And there were prosecutions for this crime.) So if you had a spell that could make your wheat walk to the next field, best not to use it.
Also, the wife of a patrician consul was prosecuted because she had said, "I wish the plebs were all dead." I don't think she had thought things through: first of all, who would she be patrician in relation to if the plebs all died? And, secondly, who would do her manual labor?