“Citrinitas” is the third of the four basic stages of alchemy. To C. G. Jung it was symbolic of growing consciousness. To the alchemists of old it meant Citrinitas (or Yellowing), which transmutes the Silver into Gold. The Citrinitas is accomplished by means of alchemical Sulphur, the Spirit of Heat.
I really love the way Jung puts a psychological spin on all things philosophical or religious!