The title of the first piece is copped from A. A. Attanasio's book Centuries, 1997. The A.E. were an earth colony on Mars trying to live "old school"--foregoing ion washes and the neural realignments of Simviv (and therefore rejecting longevity), growing their own food, and warring with the Cogs (robotic minions of the Silicon Mind). One of the colony members wrote a profound piece of music called the "Datum Surface Raga," which helped the metasapient earthling Rafe von Takawa find spiritual equilibrium, much as the datum surface expresses a kind of average level of the shifting Martian topography. The Anthropos Essentia have a secret that will not be revealed here.