When then the lion has devoured the serpent:
Then Mercury will produce a thousand fruits and flowers.
Because without the ferment of the gold this stone cannot work.
If it has found its way it will tincture that much more.
He who uses this means will persevere
and he will see that through his sighs god will be willing toward him.
In Analytical or Jungian psychology, the lion, especially the green lion, is a depiction of the cognitive identity. According to Jung, people generally develop only one dominant cognitive function and, to lesser extent an auxiliary one. The other two are not differentiated from the unconscious. Some people can use the tertiary one with a large amount or focus and efforts but the result is most of the time childish and under the general level of that cognitive function.
In our excerpt, the serpent is a depiction of those cognitive functions that are left unconscious because the serpent hides under rocks and Earth. The image of the lion devouring the serpent becomes evident: when the individual develops all his four cognitive functions, mercury, always a symbol of consciousness, will produce a thousand fruit and flowers. In fact, developing new cognitive functions is always lived as a rebirth.
The stone of the philosophers is this optimal consciousness that has two ways of perceiving, Sensation and Intuition, and two ways to hedge the perceptions, Thinking and Feeling. The stone is also called the tincture because it colors life. In the right corner of the image, we see the four colors of the elements air, earth, fire and water. Those four elements are the foundation of Jung's psychological types because both system are two pairs of opposites. The four elements have a long history of having been used to describe consciousness. Empedocles, in the 5th century BCE wrote that we see fire through fire, water through water, earth thought earth and air through air.
Finally, notice the red and the white flowers is a vase with the symbol mercury. The white flowers or white stone illustrate the first success of the process, the development of the tertiary cognitive function. The Red flower or the red stone signifies the completion of the development of the inferior cognitive function which is equal to optimal consciousness.
People generally think cognitive functions are a negligeable part of Analytical psychology but they are central to understand Jung's interpretation of Alchemy.
Benoit Rousseau
— Viridarium chymicum figuris cupro incisis adornatum, by Stoltzius von Stoltzenberg, Daniel, 1624