Original:  The nationalization of history, which had its origins more in the epics and tendentious oratory than in philosophy, sometimes grew the idea of an esprit des peuples or national spirit , and , later still , the idea that each nation had a 'mission'.
Revised:  The nationalization of history, which had its origins more in the epics and tendentious oratory than in philosophy, sometimes grew the idea of an esprit des peuples or national spirit and later still the idea that each nation had a 'mission'.
Edit intent: coherence