Here's the passage I'm trying to read: --Allons, allons, dis-je. Je sais que ce n'est plus la joie des premiers jours et que le coeur n'y est plus, mais il faut savoir entretenir la flamme sacrée. I am having trouble understanding what the last clause of this sentence means. I read it as "I know that it isn't the joy it was at first and that your heart is not in it, but it is necessary to know to maintain the sacred flame." Is this an idiom? I don't understand what it's trying to say. Thanks.