An early, unscientific form of chemistry practiced in the Middle Ages with aims including turning base metals into gold and discovering the elixir of perpetual youth, a universal cure for disease, and a universal solvent. Many alchemists were intelligent, well-meaning men and even distinguished scientists. Sir Isaac Newton, for example, was an alchemist. Pair-gain technologies such as ADSL do not involve alchemy, although sometimes they are characterized as turning copper into gold. See also pair-gain.