(1) In the long history of human development, there have been a group of invisible enemies wandering around the world like ghosts. They have brought pestilence and infectious diseases, killing people and animals and destroying villages and towns. Who are those terrible enemies? Who are they?

(2) People have been exploring, seeking these enemies and paying arduous efforts for a long period of time. This battle against death is a glorious epic. The person who kicked off this battle was an old gatekeeper of three hundred years ago.

(3) The old man was called Antony van Leeuwenhoek, and he was born in Netherlands in 1632. He loved learning since he was a child. But his family was poor and unable to afford him an education. When he was a teenager, he became an apprentice in a grocery store.

(4) However, the strong-minded little Leeuwenhoek did not give in to the tough situation. He was hardworking during the day and concentrated on reading at night. In his study of astronomy, geography, biology, he absorbed knowledge like sponge.

(5) Leeuwenhoek often went to the optician next to the grocery store to learn the techniques of lens grinding. Lens can magnify objects, which led him to a new idea: to make a piece of magnifying apparatus with high degree to observe the mysteries of nature.

(6) However, he had been rushing about for livelihood until his hair turned gray and he found a leisurely job as a gatekeeper, which allowed him to realize his dream for many years. He often spent the whole night grinding the lenses.

(7) Day after day, after he experienced many failures, and his hands were full of blood blisters, Leeuwenhoek finally made two smooth and clear lenses. The world's first ingenious microscope was finally born.

(8) This microscope could magnify objects nearly 300 times. Leeuwenhoek was fascinated totally by his new invention. He was able to observe through the lenses every tiny thing that he could collect.

(9) Once, he found an elderly man who never brushed his teeth, then took a little tartar off the elderly man's teeth and observed it through the microscope. To his surprise, he found countless micro-organism active in it!