The Dead Sea Scrolls have revealed that mashing pomegranate and figs for "profound strength and subtle form" was practiced from before 150 b.c. This is perhaps the first record of man's attempt to separate the vital juices from fruits and vegetables for their healing benefits.
Throughout the ages, herbalists and other health practitioners have grated or ground fresh herbs and soft fruits and pressed the juice along with the healing, active constituents from them. Dr. Max Gerson was the first to put forth the concept that diet could be used as cancer (and other disease) therapy, but it wasn't until the 1930s, when author and raw food proponent Dr. Norman Walker invented the first juicing machine, that juicing became widely available.
Cumbersome and yet effective, Walker's machine, called the Norwalk, first grates and squeezes fruits and vegetables. The pulp is placed into a linen bag and pressed using a hydraulic press. The first of its kind and still available, the Norwalk allowed ordinary people to effectively extract the juice from fruit and vegetables.
Around the mid-1950s, the Champion machine, the first masticating juicer, was invented. The high speed (4,000 rpm) of the turning rod causes friction, which heats the juice and destroys the live enzymes and other nutrients.
In 1993, the world's first twin-gear juice extractor, called the Greenpower juicer, was produced. It's based on the old mortar-and-pestle method of pressing out the maximum living nutrients from fruits and vegetables without losing them to heat.
Today, many great makes and models of juicing machines are available.