These factual paintings are considered to have metaphorical meaning too, the bursting into light of the phosphorus in front of a praying figure signifying the problematic transition from faith to scientific understanding and enlightenment, and the various expressions on the figures around the bird in the airpump indicating concern over the possible inhumanity of the coming age of science. These paintings represent a high point in scientific enquiry which began the undermining of the power of religion in Western societies. Some ten years later scientists worldwide would find themselves persecuted, or even put to death in the backlash to the French Revolution of 1789, itself the culmination of enlightenment thinking. Joseph Priestley, member of the Lunar Society and discoverer of oxygen would flee Britain after his laboratory in Birmingham was smashed and his house burned down in the Birmingham riots of 1791, by a mob objecting to his outspoken support for the French Revolution; and his colleague Lavoisier in France would be executed at the guillotine. The politician and philosopher Edmund Burke, in his famous "Reflections on the Revolution in France" (1790), tied natural philosophers, and specifically Priestley, to the French Revolution, writing that radicals who supported science in Britain "considered man in their experiments no more than they do mice in an air pump". In the light of this comment, Wright's painting of the bird in the air pump, completed over twenty years earlier, seems particularly prescient.