If something or someone is a necessity then it is something that you can not live without. Food, air, and water are all a necessity for life. There are many necessity quotes that can be found if you spend just a few minutes searching and you may be surprised at what you find when you start looking. Some of these sayings may be well known, others are funny, and there are others that show what happens if you do not have the basic necessities that are needed. If you own a mechanic shop then tools are a necessity in order for you to earn an income working on vehicles. Through the ages invention has come about because of necessity, and some of the most helpful inventions started because a necessary function or action was needed.