I am currently reading the RES GESTAE DIVI AVGVSTI and in the third paragraph I have come upon this sentance. Externas gentes, quibus tuto ignosci potuit, conservare quam excidere malui The general meaning I get out of this is: I have prefered to preserve rather than to fell (kill/execute) the foreign peoples whom it has been possible to spare safely. My question is: how does the relative clause in this sentance work grammaticaly? Specifically, why is potuit in the 3rd person singular perfect, while ignosci is in the present passive infinitive? My guess is that potuit is being used impersonally (it has been possible) but why is the complementary infinitive ignosci in a different tence and voice? This is one of those annoying little questions that is going to bother me until either I figure it out or someone explains it to me, so any incite into this matter would be appreciated.