This post really reminds me of the question “is it better to be loved or to be trusted?” in my opinion, to be trusted means that you are loved to an extent. I think if my worst enemy were to trust me to do something for him, there would grow a certain amount of love for him within me that will soon grow. Likewise, I would agree that usefulness really does allow us to be happy. I had a car that was an absolute dump and it had so many problems that i had no clue how to fix, such as the cigarette lighter. I didnt want to take it in and spend the money to fix it, so i decided i was going to try it out for myself. i bypassed the fuse box and wired the cigarette lighter straight to the battery and spliced in its own fuse in the middle. when it came the time to find ground, there was nothing to be found. even after scraping off the paint from the frame i still couldnt get a solid connection. so i spliced a clamp onto the end of my ground and just clamped it to a slab of metal underneath my steering wheel. and whenever i didnt have a solid connection i would just wiggle the clamp and it was all better!! though my creation was extremely white trash and dangerous, it was by far my favorite car!! i was the happiest person to drive that car because it had given me a reason to be happy driving it. I think that when we are useful we are then in turn, happy.