 By describing simple primary concepts as the “first” or “primary” subjects of logic, al-Fārābī suggests that there might be further subjects of logic. This makes sense; why shouldn’t the rules of logic apply to secondary concepts just as much as to primary concepts? In fact the way al-Fārābī has set things up would allow him to explain how this should go. Laws about secondary concepts will need tertiary concepts. But there is no need to restate the laws of logic using tertiary concepts, because “the features that attach to the primary concepts are exactly the same as those that attach to the secondary concepts”, and so on all the way up ([Letters] (9) 65.16f). 