Alchemy became known as the spagyric art after Greek words meaning to separate and to join together in the 16th century, the word probably being coined by Paracelsus. Compare this with one of the dictums of Alchemy in Latin: Solve et Coagula — Separate, and Join Together (or "dissolve and coagulate").

The best-known goals of the alchemists were the transmutation of common metals into gold (called chrysopoeia) or silver (less well known is plant alchemy, or "spagyric"); the creation of a "panacea", or the elixir of life, a remedy that, it was supposed, would cure all diseases and prolong life indefinitely; and the discovery of a universal solvent. Although these were not the only uses for the discipline, they were the ones most documented and well-known. Certain Hermetic schools argue that the transmutation of lead into gold is analogical for the transmutation of the physical body (Saturn or lead) into (Gold) with the goal of attaining immortality. This is described as Internal Alchemy. Starting with the Middle Ages, Persian and European alchemists invested much effort in the search for the "philosopher's stone", a legendary substance that was believed to be an essential ingredient for either or both of those goals. Pope John XXII issued a bull against alchemical counterfeiting, and the Cistercians banned the practice amongst their members. In 1403, Henry IV of England banned the practice of Alchemy. In the late 14th century, Piers the Ploughman and Chaucer both painted unflattering pictures of Alchemists as thieves and liars. By contrast, Rudolf II, Holy Roman Emperor, in the late 16th century, sponsored various alchemists in their work at his court in Prague.

It is a popular belief that Alchemists made contributions to the "chemical" industries of the day—ore testing and refining, metalworking, production of gunpowder, ink, dyes, paints, cosmetics, leather tanning, ceramics, glass manufacture, preparation of extracts, liquors, and so on (it seems that the preparation of aqua vitae, the "water of life", was a fairly popular "experiment" among European alchemists). Alchemists contributed distillation to Western Europe. The double origin of Alchemy in Greek philosophy as well as in Egyptian and Mesopotamian technology set, from the start, a double approach: the technological, operative one, which Marie-Louise von Franz call extravert, and the mystic, contemplative, psychological one, which von Franz names as introvert. These are not mutually exclusive, but complementary instead, as meditation requires practice in the real world, and conversely.

Several early alchemists, such as Zosimos of Panopolis, are recorded as viewing alchemy as a spiritual discipline, and, in the Middle Ages, metaphysical aspects, substances, physical states, and molecular material processes as mere metaphors for spiritual entities, spiritual states, and, ultimately, transformations. In this sense, the literal meanings of 'Alchemical Formulas' were a blind, hiding their true spiritual philosophy, which being at odds with the Medieval Christian Church was a necessity that could have otherwise led them to the "stake and rack" of the Inquisition under charges of heresy. Thus, both the transmutation of common metals into gold and the universal panacea symbolized evolution from an imperfect, diseased, corruptible, and ephemeral state towards a perfect, healthy, incorruptible, and everlasting state; and the philosopher's stone then represented a mystic key that would make this evolution possible. Applied to the alchemist himself, the twin goal symbolized his evolution from ignorance to enlightenment, and the stone represented a hidden spiritual truth or power that would lead to that goal. In texts that are written according to this view, the cryptic alchemical symbols, diagrams, and textual imagery of late alchemical works typically contain multiple layers of meanings, allegories, and references to other equally cryptic works; and must be laboriously "decoded" in order to discover their true meaning.

Psychology
Alchemical symbolism has been occasionally used by psychologists and philosophers. Carl Jung reexamined alchemical symbolism and theory and began to show the inner meaning of alchemical work as a spiritual path. Alchemical philosophy, symbols and methods have enjoyed something of a renaissance in post-modern contexts.needed

Jung saw alchemy as a Western proto-psychology dedicated to the achievement of individuation. In his interpretation, alchemy was the vessel by which Gnosticism survived its various purges into the Renaissance, a concept also followed by others such as Stephan A. Hoeller. In this sense, Jung viewed alchemy as comparable to a Yoga of the East, and more adequate to the Western mind than Eastern religions and philosophies. The practice of Alchemy seemed to change the mind and spirit of the Alchemist. Conversely, spontaneous changes on the mind of Western people undergoing any important stage in individuation seems to produce, on occasion, imagery known to Alchemy and relevant to the person's situation.

His interpretation of Chinese alchemical texts in terms of his analytical psychology also served the function of comparing Eastern and Western alchemical imagery and core concepts and hence its possible inner sources (archetypes).

Marie-Louise von Franz, a disciple of Jung, continued Jung's studies on Alchemy and its psychological meaning.

Magnum Opus
The Great Work; mystic interpretation of its four stages:

Nigredo (-putrefactio), blackening (-putrefaction): corruption, dissolution, individuation, see also Suns in alchemy - Sol Niger
Albedo, whitening: purification, burnout of impurity; the moon, female
Citrinitas, yellowing: spiritualization, enlightenment; the sun, male
Rubedo, reddening: unification of man with God, unification of the limited with the unlimited.

After the 15th century, many writers tended to compress citrinitas into rubedo and consider only three stages.

However, it is in citrinitas that the Chemical Wedding takes place, generating the Philosophical Mercury without which the Philosopher's Stone, triumph of the Work, could never be accomplished.

Within the Magnum Opus was the creation of the Sanctae Moleculae, that is the 'Sacred Masses' that were derived from the Sacrae Particulae, that is the 'Sacred Particles', needed to complete the process of achieving the Magnum Opus.