Other related topics at:
All In Your Mind
656. Happiness; Security
"To make any happiness sincere it is necessary that we believe it
to be lasting; since whatever we suppose ourselves in danger of
losing must be enjoyed with solicitude and uneasiness, and the
more value we set upon it, the more must the present possession
be imbittered."
Johnson: Rambler #53 (September 18, 1750)
Link