Yellow corresponds the the citrinitas, the third stage of the magnum opus or great work of the alchemist. It is the solar consciousness making itself known in the lunar, watery realms represented by the swamps. The integration of this enlightened consciousness must be allowed to happen slowly, lest it turn to delusion. By a slow, gentle application of heat (focus/fire/consciousness) and patience (passivity/water/moon) the adept enters the next and final phase, the rubedo, or the reddening, in which the enlightened awareness solidifies into the philosopher’s stone.