Plato supposed that matter was formed of particles shaped like regular solids. This hypothesis seemed confirmed, in the first half of the 17th century, by microscopic observation of saline crystals, giving rise to a number of new theories on the ultimate structure of matter. Along with the speculative and alchemistic traditions, both medieval and modern chemistry had been characterized by the practice of preparing pharmaceutical remedies by manipulating plants, animals and minerals. The instruments used for these practices were extremely basic, not differing greatly from ordinary kitchen implements.