The term nostalgia describes a longing for the past, often in idealized form. The word is made up of two Greek roots (νόστος nostos "returning home", and άλγος algos "pain"), to refer to "the pain a sick person feels because he wishes to return to his native home, and fears never to see it again". It was described as a medical condition, a form of melancholy, in the Early Modern period, and came to be an important topic in Romanticism.
The term was coined in 1688 by Johannes Hofer (1669-1752) in his Basel dissertation. Hofer introduced nostalgia or mal du pays "homesickness" for the condition also known as mal du Suisse "Swiss illness" or Schweizerheimweh "Swiss homesickness", because of its frequent occurrence in Swiss mercenaries who in the plains of lowlands of France or Italy were pining for their native mountain landscapes. English homesickness is a loan translation of nostalgia. Cases resulting in death were known and soldiers were sometimes successfully treated by being discharged and sent home. Receiving a diagnosis was, however, generally regarded as an insult.