As with all fill in the blank questions, if you are operating out of a course text or lecture notes that feature the correct answer, I would go to that source before anything else. I do think that several words could fit in the blank and capture the spirit of the sentence. One word would be "optimism." The Romantic thinkers saw the French Revolution as creating a sense of optimism in Europe in the idea of new era dawning. For Romantic thinkers who fell in love with the ideals of the French Revolution, the belief was that the French Revolution was the embodiment of new values that would transform Europe.
Another word that could fit here would be "excitement. The Romantic thinkers like Wordsworth, Coleridge, and Blake were sincerely excited and galvanized by the promises and possibilities of the French Revolution. They saw it as a moment in time, an instant to be " thrilled and inspired by the notion of revolutionaries rising up and demanding their rights." Both terms fit because they are able to connect the idea of the French Revolution to something new emerging in Europe. This construction is how the Romantic thinkers saw the French Revolution.