Transmutation is the process of changing one substance into another. In chemistry, it often refers to the transformation of one element into another through nuclear reactions. This can occur naturally, such as in radioactive decay, or artificially in laboratories using particle accelerators. In the context of alchemy, transmutation refers to the mythical process of turning base metals, like lead, into precious metals, such as gold. Alchemists believed that this transformation could also lead to the creation of the Philosopher's Stone, a legendary substance that could grant immortality and ultimate wisdom.