Shadow", Chapter 2, Part 2

For my part, I had already adopted as my own the device graved in bronze above the door of a certain mausoleum. They were a fountain rising above waters, and a ship volant, and below these a rose.

The fountain is a symbol of the life-force, purification, and rebirth (e.g. the Fountain of Life). The ship is a symbol of adventure, a journey (e.g. the journey from this world to the next), and to Christians the soul's refuge on the sea of troubles. Severian's ship is flying, which is a symbol of freedom (since the sky is a symbol of spirituality, possibly the freedom from the earthly material world). Also, a flying ship has the more literal interpretation of a spaceship. Below both of these, which might mean it's the foundation for them, is the rose. It's most commonly a symbol of love, but since we don't know what color the rose is, it could mean a number of things. Different color roses have symbolized love, martyrdom, faith, purity, beauty, grace, completion, achievement, perfection, joy, secrecy, silence, mystery, delicacy, transience, jealousy, friendship, elegance... you get the idea. Its interpretation is problematic. Roses appear later in the book, too, so maybe that will narrow down the possibilities. Severian describes watching the secret life of animals from his hidden place:

A moment suffices to describe these things, for which I watched so long. The decades of a saros would not be long enough for me to write all they meant to the ragged apprentice boy I was. Two thoughts (that were nearly dreams) obsessed me and made them infinitely precious. The first was that at some not-distant time, time itself would stop... the colored days that had so long been drawn forth like a chain of conjuror's scarves come to an end, the sullen sun wink out at last. The second was that there existed somewhere a miraculous light - which I sometimes conceived of as a candle, sometimes as a flambeau - that engendered life in whatever objects it fell upon, so that a leaf plucked from a bush grew slender legs and waving feelers, and a rough brown brush opened black eyes and scurried up a tree.

Did I mention that his hidden place is the mausoleum, a tomb, situated in the necropolis (city of death) that completely surrounds his home? So in the midst of death, he is observing life, and finding it precious. His first thought is about death. Possibly just his own death, or maybe the death of everything. This makes life infinitely precious, because it could stop at any moment. His second thought is about the force that generates life. Maybe the things he saw were infinitely precious because they were examples of this force at work. That one I'm less sure about. Suggestions are welcome.