Opus (The Fool's Rose Garden)

"The album booklet defines sagyou (“work”) as the task of transforming metal into gold through the three stages known as nigredo, albedo, and rubedo. This would also purify the alchemist’s spirit, and thus the true transformation took place within the soul. The entire process of creating the [Philosopher’s Stone is called the Magnum Opus (“Great Work”).

To quote from the Wikipedia entry on alchemy, specifically the beginning of the Relation to Hermeticism section: “In the eyes of a variety of esoteric and Hermetic practitioners, the heart of alchemy is spiritual. Transmutation of lead into gold is presented as an analogy for personal transmutation, purification, and perfection. This approach is often termed 'spiritual’, 'esoteric’, or 'internal’ alchemy”.

As for the second part of the title, there’s a 16th century alchemical treatise called the Rosarium Philosophorum, or The Rosary of the Philosophers. A rosarium, which in this context means “rose garden”, is a metaphor for a collection of wise sayings from other philosophers (Geber, Hermes Trismegistus, Aristotle, Plato, and the like).

You can view a summary of the Rosarium Philosophorum along with many images from it here."

Lyrics

 * 1 "The Rosarium Philosophorum contains a classical alchemical image of a green lion devouring the sun, but the one here is mentioned as having wings, so perhaps it’s supposed to be a reference to a Griffin or Sphinx…?"
 * 2 "A king and a queen personifying the sun and moon also appear in the Rosarium Philosophorum. In the Kenja no Puropera Interactive Live Show, the Gardener King character makes an appearance in the very first song, and the lyrics for “[[Nigredo (Blackening)|Nigredo” mention a Queen, along with night-related imagery.
 * In addition to the contrasting imagery of the sun/day and moon/night here, you also have soot and rust, the former of which is associated with fire, and the latter with water. Day/night and fire/water imagery also appears in the lyrics for “Kenja no Puropera”."