A definition of transmutation by Roberto Assagioli from his book Psychosynthesis.
“Once the choice of the ideal form has been made, practical psychosynthesis, the actual construction of the new personality, begins. This work may be divided into three principal parts:
Utilization of the available energies. These are (a) the forces released, by the analysis and disintegration of the unconscious complexes; (b) the tendencies latent, and until now neglected, which exist on the various psychological levels. Such utilization demands the transmutation of many of these unconscious forces. Their inherent plasticity and mutability makes this possible. In fact, such transmutation is a process that is continually taking place within us. Just as heat is changed into motion and electric energy, and vice versa, our emotions and impulses are transformed into physical actions or into imaginative and intellectual activities. Conversely, ideas stir up emotions or are transformed into plans and hence into actions.
Instances of such transformations have been observed and recognized by many people. When the Latin poet says, “Facit indignatio versus” (Indignation produces my poems) he shows that he has realized how an emotional wave of indignation, if denied a natural outlet through external action, can be transformed into poetic activity. Again, when Heine writes, Aus meinen grossen Schmerzen much’ ich die kleinen Lieder (Out of my great suffering I produce my little songs) he indicates that his pain has been sublimated into poetry, and thus transfigured into beauty.
Important teachings and examples concerning the doctrine and practice of this transformation of the inner energies can be found in the yoga of the Hindu, in Christian mysticism and asceticism and in works on spiritual alchemy, while some points have been contributed by psychoanalysis. We, therefore, possess sufficient elements for the formation of a science of psychological energies (psychodynamics), and of reliable and adequate techniques by which to bring about the desired changes in ourselves and in others.” (Psychosynthesis, p. 24-25)
Here is another short text from the Assagioli Archive in Florence:
The Transmutation of Sensuality
“Infinite Life, throughout myriad eras, has been immersing itself in form, in matter … … Thus, our “I”, imprisoned and limited in the body, obscured by dense clouds of passion, continually agitated and distracted […], has lost the memory of its divine origin and its intrinsic nobility. We live in the midst of a quantity of passion and vanity that are always harmful and wasteful, even when they simply appear useless. This is the conclusion that, without turning to asceticism, anyone who considers the point of view of spiritual evolution, is forced. “Good is what benefits evolution, bad is what hinders it.” Thus, any dissipation of any force is bad. Therefore, immoderate luxury, avarice and debauchery are the cause of future suffering. The principle, value and necessity of asceticism lie in the achievement of full self-control and inner freedom through purification, detachment and discipline. Maintain a dual attitude at the same time: maximum dominion over external things and over our internal elements, and maximum obedience to the “King” whose throne is in the mysterious center of our soul – this is the motto for each of us. Lord of the world, servant of the Spirit. Ancient asceticism was effective and often heroic, but it used artificial methods which were too violent: it aimed too much to produce physical pain, was conceived too separatively and often tended to become an end in itself. There is however another alternative, there is a more dynamic and constructive way. This method is based on a fundamental property of biological and psychological energies, that is, their possibility of transmutation. By means of elevation, the purely physical sexual instinct can in fact be transformed into emotional love; and the desire for sensual pleasures into aspiring to joys of an aesthetic, intellectual and spiritual nature.”