In my opinion, the most important discovery in the history of mankind is 'Discovery of fire'. In more modern world, an important discovery that explained a lot of unknowns was 'Discovery of gravity by Newton'. More recently, the studies of DNA's have yielded some important discoveries and path to discoveries for many studies/researches. There are ample examples in scientific world where we discover something by accident.
If we take the above 3 examples for now, it may be fair to assume that discovery of Fire was an accident and hence not much study or focus may have been required. Again, discovery of Gravity has been accredited to the event of Newton seeing an apple falling. I would like to give some more credit to Newton here. He must have seen things falling down since his early days. So what triggered the event of him realizing the existence of gravity on that particular day. I assume he was working on that subject on some of his many projects and hence he was focused enough that day to see the event of falling of the apple as the action of gravity. Technically Dr. Friedrich Miescher was the first one to discover/notice, when he was once studying pus from a surgical wound and found a strange microscopic substance in the nucleus of the cell that needed further investigation. It was further researched by other scientists and finally Watson and Crick solved the mystery behind DNA.
At this point, I would like to ask the question, which of the two examples is an important discovery. A) If during the study of some medical research, I as a scientist discover after years of patient and focused study a medicine that cures cancer. B) If during a hiking trip I eat a fruit, as I am out of my factory processed, preservative added fruit candy bars, and discover that the fruit miraculously cured my diabetes in a minute. Which of the two is an important discovery? Sure, both are as important as the other. Although in case of the later there was no focused study or...