The central image of alchemy is the idea of the opus. The alchemist thought of himself as committed to a sacred work – a search for the supreme and ultimate value. Alchemical texts have a great deal to say about the nature of the opus and the attitude that should be taken towards it. Certain virtues are indispensable prerequisites... There are requirements of ego functions. Patience is basic. Courage means a willingness to face anxiety. Continuous regimen means that through all shifts of mood and mental state one is willing to persevere in the effort to scrutinize and understand what is happening.

     ...A careful awareness of the transpersonal level of the psyche is required. This means one must be Self-oriented rather than ego-oriented. There is a paradox here—as so often in alchemy and psychotherapy. An awareness of the Self and the religious attitude that such an awareness brings are the goals of psychotherapy rather than requirements at the beginning. However, the potential at least must exist from the start. As one alchemist says, one must start with a bit of the Philosophers' Stone if one is to find it. As the process deepens, one realizes more and more that insights come by grace and that development occurs not by the will of the ego but by the urge to individuation from the Self. 

      Another aspect of the opus is that it is a highly individual work. Alchemists were decidedly solitaries. They might have had one helper but no more. This refers to the uniquely individual nature of individuation. In its deepest aspects it is experienced alone. The opus cannot be performed by a committee. It thus generates a certain unavoidable alienation from the world, at least for a time. 

      Another feature of the opus concerns its secret nature. The alchemists considered themselves to be the guardians of a mystery that was not to be divulged to the unworthy. 

      The basic scheme of the opus is quite simple. It is as follows: The purpose is to create a transcendent, miraculous substance, which is variously symbolized as the Philosopher's Stone, the Elixir of Life, or the universal medicine. The procedure is, first, to find the suitable material, the so-called prima materia, and then to subjected to a series of operations that will turn it into the Philosopher's Stone.

E. Edinger

      The basis of the opus, the prima materia, is one of the most secrets of alchemy. This is hardly surprising, since it represents the known substance that carries the projection of the autonomous psychic content. It was of course impossible to specify such substance, because the projection emanates from the individual and is consequently different in each case. ... For one alchemist the prima materia was quicksilver, for others it was ore, iron, gold, lead, salt, sulphur, vinegar, water, air, fire, earth, blood, water of life, lapis, poison, spirit, cloud, sky, dew, shadow, sea, mother, moon, dragon, Venus, chaos, microcosm.

C.G. Jung

      Prima materia – first matter, the original, pure substance from which it was believed the universe was created and into which it might again be resolved. The alchemical prima materia is the receptive matter upon which the forms of all things were thought to be imprinted in the process of creation. 

      According to the alchemists, the philosopher’s stone could not be made, nor base metals transmuted into silver and gold, without their first being dissolved into the original substance or first matter.

L. Abraham

      It is very difficult to understand alchemy as we find it in the original writings. We encounter a wild, luxuriant, tangled mass of overlapping images that is maddening to the order-seeking conscious mind. My method of ordering the chaos of alchemy is to focus on the major alchemical operations. After the prima materia has been found, it has to submit to a series of chemical procedures in order to be transformed into the Philosophers' Stone. Practically all of alchemical imagery can be ordered around these operations, and not only alchemical imagery. Many images from myth, religion, and folklore also gather around these symbolic operations, since they all come from the same source—the archetypal psyche.

      There is no exact number of alchemical operations, and many images overlap. I have chosen seven operations as the major ones making up the alchemical transformation. They are calcinatio, solutio, coagulatio, sublimatio, mortificatio, separatio, and coniunctio. Each of these operations is found to be the center of an elaborate symbol system. These central symbols of transformation make up the major content of all culture-products. They provide basic categories by which to understand the life of the psyche, and they illustrate almost the full range of experiences that constitute individuation.

E. Edinger​​

      Coniunctio and the ensuing death is sometimes expressed in terms of hieros gamos: the two principles—the Sun and Moon, King and Queen, unite in the mercury bath and die (this is the nigredo): their 'soul' abandons them to return later and give birth to the filius philosophorum, the androgynous being (Rebis) which promises the imminent attainment of the Philosopher's Stone. 

M. Eliade

      In the age-old image of the uroboros lies the thought of devouring oneself and turning oneself into a circulatory process, for it was clear to the more astute alchemists that the prima materia of the art was man himself. The uroboros is a dramatic symbol for the integration and assimilation of the opposite, i.e., of the shadow. This “feed-back” process is at the same time a symbol of immortality, since it is said of the uroboros that he slays himself and brings himself to life, fertilizes himself and gives birth to himself. He symbolizes the One, who proceeds from the clash of opposites, and he therefore constitutes the secret of the prima materia which, as a projection, unquestionably stems from man’s unconscious.

C.G. Jung

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      The uroboros, the circular snake biting its tail, is the symbol of the psychic state of the beginning, of the original situation, in which man's consciousness and ego were still small and undeveloped. As symbol of the origin and of the opposites contained in it, the uroboros is the "Great Round," in which positive and negative, male and female, elements of consciousness, elements hostile to consciousness, and unconscious elements are intermingled. In this sense the uroboros is also a symbol of a state in which chaos, the unconscious, and the psyche as a whole were undifferentiated—and which is experienced by the ego as a borderline state.

      The uroboric totality also appears as a symbol of the united primordial parents from whom the figures of the Great Father and the Great Mother later crystallized out. Thus it is the most perfect example of the still undifferentiated primordial archetype. Although its paradoxical and polyvalent character is not evident in the seemingly simple symbol of the circular snake, it becomes evident as soon as we attempt to differentiate all the inexhaustible meanings contained in this symbol.

E. Neumann

      The much sought-after goal of the opus alchymicum and the most famous of all alchemical ideas. The Stone is the arcanum of all arcana, possessing the power to perfect imperfection in all things, able to transmute base metals into pure gold and transform the earthly man into an illumined philosopher. ... The Stone is known as the universal medicine because it can dispel all corruption, heal all disease and suffering, and bestow youth, longevity and wisdom. Calid had stated that "This Stone is to be found at all times, in everie place, and about every man" (Boohe of the Secrets, 40). This tradition was inherited by the medieval alchemists and the alchemists of Renaissance Europe. Many were aware of the fact that the Stone or the matter for making the Stone was to be found in man himself.

L. Abraham

      The union of opposites in the stone is possible only when adept has become One himself. The unity of the stone is the equivalent of individuation, by which man is made one; we would say that the stone is a projection of the unified self. This formulation is psychologically correct. It does not, however, take sufficient account of the fact that the stone is a transcendent unity. We must therefore emphasize that though the self can become a symbolic content of consciousness, it is, a supraordinate totality, necessarily transcendental as well. Dorn recognized the identity of the stone with the transformed man when he exclaimed: "Transmute yourselves from dead stones into living philosophical stones!" But he lacked the concept of an unconscious existence which would have enabled him to express the identity of the subjective psychic center and the objective alchemical center in a satisfactory formula.

C.G. Jung

      Alchemical evolution is epitomized in the formula Solve et Coagula — that is to say, “Analyze all the elements in yourself, dissolve all that is inferior to you, even though you may break in doing so; then with the strength acquired from the preceding operation, congeal".

      Evola (Tradizione Ermetica) writes: “Our Work is the conversion and change of one being into another being, one thing into another thing, weakness into strength, bodily into spiritual nature”.

J.E. Cirlot

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      The chemical putrefaction is compared to the study of the philosophers, because as the philosophers are disposed to knowledge by study, so natural things are disposed by putrefaction to solution. To this is compared the philosophical knowledge, for as by solution bodies are dissolved, so by knowledge are the doubts of the philosophers resolved.

G. Dorn