No-they do not expire. No US stamps issued since 1865 have been been devalued. The only exception are the special delivery stamps which paid for service no. longer offered. Air mail stamps are good for any purpose. Some stamps can't be used for certain things.
the pure and concentrated essence of a substance. 2. the most perfect embodiment of something. 3. (in ancient and medieval philosophy) the fifth essence or element, ether, supposed to be the constituent matter of the heavenly bodies, the others being air, fire, earth, and water. Origin of quintessence.
Quintessence literally means fifth element.. Some people refer to this element as spirit. There is no standard symbol for spirit. Circles are probably the most commonly used symbol for it, but spirals are also sometimes utilized.. By Catherine Beyer. Spirals are some of the oldest geometric shapes in ancient artwork dating back at least to the Neolithic period, the product of people thousands of years away from having access to writing.