When you buy something it starts to depreciate. A car will be less reliable next year than it is now. If one of our customers installs a new cable this year, it will be less reliable next year, and even less reliable the following year. We all recognize this phenomenon as the aging process. The black line in the graph below is the post-installation failure rate for new cables installed at a U.S. Southwestern utility between 1969 and 2005.* In general, and as expected, failures increase as the years since installation increase.
There were three bricklayers just beginning a new project together. When each was asked individually what they were doing, they gave three very different answers. The first bricklayer gruffly replied that he was laying bricks. The second revealed that he was building a church. The third bricklayer proclaimed he was building the house of God! The first bricklayer had a job; the second bricklayer had a career; the third had a calling.