The philosophes (French for philosophers) were rational men. They valued the human mind and reason above all, and this often got them into hot water with the Catholic Church, still a formidable social and political institution in Europe. Just as we now believe that only 10 percent of the brain is utilized and the remaining untapped potential is enormous, the philosophes believed that the development and deployment of human reason could and should unleash a Golden Age, with advancements in every field of human endeavor. Nature took precedence over classical philosophy and the Bible in the theories of these men. They believed that people should be active and engaged in this life, and not fretting or planning for either damnation or paradise in the next. They assaulted the Church with caustic tongues and quill pens dipped in vitriol and often found themselves locked up or on the run as a result.
These philosophes were more than deep thinkers. In the age of powdered wigs and pantaloons, they were flashy showmen and celebrities in their lifetimes. They sought to aggressively change the world through word and deed and not merely passively sit in the pose of Rodin's sculpture of the Thinker and speculate on what it was all about.
Be careful what you put on paper. All the great thinkers of the enlightenment paid a price for espousing their beliefs. Those were the days when the powers-that-be could have your head for expressing a dissenting opinion. Many spent time in prison and exile for their writings.
The American Revolution was hailed as an example of their theories put into practice. In their own homeland, the French Revolution was a bloody and barbaric affair and led to the rise of Napoleon. Love him or hate him, it is safe to say that Bonaparte was not an aficionado of democracy. Though the terrors of the French Revolution were used by the Enlightenment's detractors to denounce it as a failed philosophy, its success across the pond in America vindicated the Illuminists, as they are also called. The philosophers of the Enlightenment left a legacy that continued to inspire and illuminate the minds and hearts of humankind in the nineteenth and twentieth centuries. The three most noteworthy philosophes are Montesquieu, Voltaire, and Rousseau.