Literature, most generically, is any body of written works. More restrictively, literature writing is considered to be an art form, or any single writing deemed to have artistic or intellectual value, often due to deploying language in ways that differ from ordinary usage.
The death of Dr. Hudson is a loss to the republick of letters.
William King, letter (Jan. 7, 1719). Same phrase occurs in the Spectator. Commonwealth of letters is used by Addison, Spectator, No. 529. Nov. 6, 1712.
The brightness of the Sun varies on all time scales and wavelengths. An EU-funded initiative is gathering scattered observations from over 25 instruments to accurately represent how solar irradiance variability influences Earth's climate.