Unicorn in the Garden" by James Thurber is a classic example of the existentialist philosophy of choice and subjectivity, as shown by the characterization of the man, his wife, the police and the psychiatrist.
As the story opens we find a man sitting at home eating breakfast with his wife upstairs asleep. The man, who chooses to glory in his existence by rising and eating, is blessed with the spectacle of a unicorn in his garden. The man is happy. The unicorn eats his roses. The wife has chosen to sleep and ignore the beautiful day, but in so doing has negated further choices she might have made had she woken up. The two times the man attempts to wake his wife to the life around her and in the garden, she further confirms her lack of interest in life and living the moment that has presented itself. The wife ignores and insults her husband for believing that a unicorn exists.