The first of what is intended to be a series of short articles about discoveries and inventions that revolutionised the human condition.
We'll never know who first discovered how to make a continuous sharp edge. Perhaps it was a discovery of many places at various times. What is certain is that, with this ability, early man set himself apart from every other creature on the earth, for although some use twigs and stones as tools no other consciously creates them. With a sharp edge you can create a hand axe. With a hand axe you can cut small branches. When you can cut small branches you can make a haft for your axe. When you can make a haft for your axe you can use the principle of the lever to cut bigger branches. From these simple tools you can navigate your way to complex tools, and once you have complex tools you can make anything. Eventually you get to the point where you can cut sharp sticks; fishing and hunting are made much easier. Then you can make spears; these keep you out of the attack range of whatever unfortunate creature you are attempting to have for dinner whilst still attacking it effectively. Still later your blade will allow you to make ropes and nets; now trapping and fishing are made simple and you can feed large numbers with minimal effort.
No.1 - The Blade.
The cutting edge is a device that has served humanity since before history began; from flint stones knapped to a sharp edge, through the sickle, scythe, carving knife, lathe-tool and scissors, and it's only in the last half-century or so that we have begun to forgo the blade for high-pressure water and compact streams of photons. For most of us a knife or pair of scissors or some other bladed instrument is still vital in our day-to-day activities. Any technology that was ancient in Archimedes' time and is still in the same basic form (though with improved materials) being used widely and commonly today surely deserves to be called revolutionary.