Philo Taylor Farnsworth invented the current system of television transmission (传输) and reception in 1928, and it was considered one of the great scientific inventions of the 20th century. It was remarkable because the young inventor had just celebrated his 22nd birthday.

Farnsworth had desired to be an inventor since the age of six. Farnsworth was just 14 when he had the idea of television. On August 26, 1930, about a decade after first having the idea that was the basis of his invention, he received the patent (专利) on the electronic television system. By the end of his life, he had held more than 300 patents.

Farnsworth wasn’t the first person to dream up television, but he was the first person to find a way to make it work without a mechanical aspect. The biggest problem that inventors faced was how to transmit image data. Farnsworth’s central innovation was to imagine a way of doing it that relied on electronic technology alone, and so wouldn’t be slowed down by the abilities of a mechanical image-transmitting system.

Farnsworth dreamed up his idea while he was driving a horse-drawn harrow (耙) on the family’s new farm in Idaho. As he was plowing (犁) a potato field in straight, parallel (平行的) lines, he saw television. He imagined a system that would break an image into horizontal (水平的) lines and put those lines back together into a picture at the other end. In 1927, Philo and his wife Elma watched as he made the first transmission: A horizontal line was transmitted to a receiver in the next room. Two years after that first transmission, Farnsworth sent an image of Elma and her brother, making her the first woman on TV.

Farnsworth thought his invention had realistic prospects. “If we were able to see people in other countries and learn about our differences, why would there be any misunderstandings?” he asked. “War would be a thing of the past.”

When the great library of Alexandria burned, the story goes, one book was saved. But it was not a valuable book, and a poor man got it.

The book wasn't very interesting, but between its pages there was something very interesting indeed. It was a thin strip of vellum on which was written the secret of the “Touchstone”．

The touchstone was a small pebble that could turn any common metal into pure gold.

The writing explained that it was lying among thousands and thousands of other pebbles that looked exactly like it. But the secret was this: The real stone would feel warm, while ordinary pebbles are cold.

So the man sold his house, bought a tent, camped on the seashore, and began testing pebbles. He knew that if he picked up normal pebbles and threw them down again because they were cold, he might pick up the same pebbles hundreds of times. So, when he felt one that was cold, he threw it into the sea. He spent a whole day doing this but none of them was the touchstone. Yet he went on and on this way. Pick up a pebble. Cold—throw it into sea. Pick up another. Throw it into the sea. The days stretched into months and the months into years.

One day, however, about mid-afternoon, he picked up a pebble and it was warm. He threw it into the sea before he realized what he had done. He was used to throwing each pebble into the sea as soon as he picked it up. So when the one he wanted came along, he still threw it away.

So it is with opportunity. Unless we are vigilant, it's easy to fail to realize an opportunity when it is in hand and it's just as easy to throw it away.