ax to grind

If one is not just writing history but also trying to condemn and “demolish” one’s enemy, as Neumann is, you need a deeper level of introspection, and a high standard of proof. If not, it’s better to let “silence be a fence for wisdom.” (Pirkei Avot 3:13) It’s not possible to maintain the curiosity and openness you need for real research if you have such a big ax to grind.