- Light, visible light, or visible radiation is electromagnetic radiation that can be perceived by the human eye. Visible light spans the visible spectrum and is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 terahertz. The visible band sits adjacent to the infrared (with longer wavelengths and lower frequencies) and the ultraviolet (with shorter wavelengths and higher frequencies), called collectively optical radiation.
- Jean-Jacques Rousseau (Wikipedia)
Jean-Jacques Rousseau (UK: /ˈruːsoʊ/, US: /ruːˈsoʊ/ French: [ʒɑ̃ ʒak ʁuso]; 28 June 1712 – 2 July 1778) was a Genevan philosopher (philosophe), writer, and composer. His political philosophy influenced the progress of the Age of Enlightenment throughout Europe, as well as aspects of the French Revolution and the development of modern political, economic, and educational thought.