Nostalgia is a poignant and pleasant experience

And by the early 20th century,professionals no longer viewed it
as a neurological disease,but as a mental condition similar to depression.Psychologists of the time speculated that it represented difficulties letting go of childhood,or even a longing to return to one's fetal state.But over the next few decades,the understanding of nostalgia changed in two important ways.Its meaning expanded from indicating homesickness to a general longing for the past.
And rather than an awful disease,it began to be seen as a poignant and pleasant experience.