When you look back at them, many of the fundamental discoveries of science seem so simple, too absurdly simple. How was it men groped and fumbled for so many thousands of years without seeing things that lay right under their noses? So with microbes. Now all the world has seen them cavorting on movie screens, many people of little learning have peeped at them swimming about under lenses of microscopes, the greenest medical student is able to show you the germs of I don’t know how many diseases--what was so hard about seeing microbes for the first time? But let us drop our sneers to remember that when Leeuwenhoek was born there were no microscopes but only crude handlenses that would hardly make a ten-cent piece look as large as a quarter. Through these--without his incessant grinding of his own marvelous lenses--that Dutchman might have looked till he grew old without discovering any creature smaller than a cheese-mite. You have read that he made better and better lenses with the fanatical persistence of a lunatic; that he examined everything, the most intimate things and the most shocking things, with the silly curiosity of a puppy. Yes, and all this squinting at bee-stings and mustache hairs and whatnot were needful to prepare him for that sudden day when he looked through his toy of a gold-mounted lens at a fraction of a small drop of clear rain water to discover-- What he saw that day starts this history. Leeuwenhoek was a maniac observer, and who but such a strange man would have thought to turn his lens on clear, pure water, just come down from the sky? What could there be in water but just--water? You can imagine his daughter Maria--she was nineteen and she took such care of her slightly insane father!--watching him take a little tube of glass, heat it red hot in a flame, draw it out to the thinness of a hair.... Maria was devoted to her father--let any of those stupid neighbors dare to snigger at him!--but what in the world was he up to now, with that hair-fine glass pipe? You can see her watch that absent-minded wide-eyed man break the tube into little pieces, go out into the garden to bend over an earthen pot kept there to measure the fall of the rain. He bends over that pot. He goes back into his study. He sticks the little glass pipe onto the needle of his microscope.... What can that dear silly father be up to? He squints through his lens. He mutters guttural words under his breath.... Then suddenly the excited voice of Leeuwenhoek: “Come here! Hurry! There are little animals in this rain water.... They swim! They play around! They are a thousand times smaller than any creatures we can see with our eyes alone.... Look! See what I have discovered!”