It acts as a Conduit for what we call Sha

“Terrible Feng Shui here. Worst I ever saw. You two crazy?”

“Because of…?” Dixon indicating behind them, in thickening dusk, the Visto sweeping away.

“It acts as a Conduit for what we call Sha, or, as they say in Spanish California, Bad Energy.— Imagine a Wind, a truly ill wind, bringing failure, poverty, disgrace, betrayal,— every kind of bad luck there is,— all blowing through, night and day, with many times the force of the worst storm you were ever in.”

“No one intends to live directly upon the Visto,” Mason speaking as to a Child. “The object being, that the people shall set their homes to one side or another. That it be a Boundary, nothing more.”

“Boundry!” The Chinaman begins to pull upon his hair and paw the earth with brocade-slipper’d feet. “Ev’rywhere else on earth, Boundaries follow Nature,— coast-lines, ridge-tops, river-banks,— so honoring the Dragon or Shan within, from which Land-Scape ever takes its form. To mark a right Line upon the Earth is to inflict upon the Dragon’s very Flesh, a sword-slash, a long, perfect scar, impossible for any who live out here the year ‘round to see as other than hateful Assault. How can it pass unanswer’d?”

Mason & Dixon, by Thomas Pynchon (p542).