What is Understood by Fire Used Figuratively.
Fire, particularly in poetry, often signifies love, and is employed more elegantly in the plural than in the singular. Corneille often says "un beau feu" for a virtuous and noble love. A man has fire in his conversation; that does not mean that he has brilliant and enlightened ideas, but lively expressions animated by action.
Fire in writing does not necessarily imply lightness and beauty, but vivacity, multiplied figures, and spontaneous ideas. Fire is a merit in speech and writing only when it is well managed. It is said that poets are animated with a divine fire when they are sublime; genius cannot exist without fire, but fire may be possessed without genius.
FIRMNESS.
Firmness comes from firm, and has a different signification from solidity and hardness; a squeezed cloth, a beaten negro, have firmness without being hard or solid.
It must always be remembered that modifications of the soul can only be expressed by physical images; we say firmness of soul, and of mind, which does not signify that they are harder or more solid than usual.
Firmness is the exercise of mental courage; it means a decided resolution; while obstinacy, on the contrary, signifies blindness. Those who praise the firmness of Tacitus are not so much in the wrong as P. Bouhours pretends; it is an accidental ill-chosen term, which expresses energy and strength of thought and of style. It may be said that La Bruyère has a firm style, and that many other writers have only a hard one.