• Nostalgia was considered by the early 20th century a psychiatric illness caused by some traumatic experience of childhood. It had three components, cognitive, affective and conative.
• The cognitive part remembered old memories of the self, while the affective part was a sad emotion, finally moving towards a desire to return home(conative).
• Nostalgia is neither a pathological state and nor is it necessarily beneficial. What we can think, remember or imagine, is not bound to be real or factual.

Having nostalgic thoughts about the past that one hasn’t directly experienced or lived through is called _Anemoia_.

The cognitive component of nostalgia is often a mental simulation, and may not have happened for real in the lifetime of the reminiscing person.

Sadness and depression are associated with the feeling of nostalgia, and recent studies show that nostalgia might even be caused by these negative emotions.

Loneliness, loss, a sense of meaninglessness, boredom and even coldness can trigger nostalgia.

• When the reminiscing person adds certain false memories and desirable traits to the past event, this creates a paradox and is attributed to an ancient Greek sophist and philosopher, Gorgias.
• A Platonic Paradox is when a person desires something and when it is finally attained, the satisfaction that was supposed to come with the attainment is not there.