My other grandpa wrote his answer in an email to my mom, "The most significant invention created in my lifetime was the heart-lung machine, which enabled surgeons to perform open-heart surgery, and without which I would have probably died 15 or more years ago. So, you see, it's the most important invention TO ME. You might explain that the heart-lung machine circulates the blood throughout your body during surgery, while the surgeons perform the heart operation. You will recall that I had my procedure June 10, 1992."
What do you think is the most important invention that has happened during your life?