All religions have periods in their history which are looked back to with retrospective fear and trembling as eras of persecution, and each religion has its own book of martyrs.

Le Gallienne is pointing to a recurring pattern in religious history: movements that begin as persecuted minorities often, once established, develop institutions capable of persecuting others. The “retrospective fear and trembling” suggests later generations’ moral unease when confronting their tradition’s coercive episodes—Inquisitions, sectarian wars, expulsions, or state-enforced orthodoxy. By saying each religion has its own “book of martyrs,” he underscores how communities preserve narratives of suffering to define identity and legitimacy. The implication is double-edged: remembrance can inspire conscience and humility, but it can also be wielded polemically, justifying suspicion or retaliation. The quote thus functions as a warning against sanctifying victimhood while ignoring one’s capacity for intolerance.