The originators of the two-stage defense program did not compensate sufficiently for chance nor for the psychological effect of visible extermination of this avid foe. For it was psychologically reassuring and deeply satisfying to the endangered Pernese to see the menace charred to impotence in mid-air. Also, the southern continent, where the second phase was initiated, proved untenable and the entire colony was moved to the northern continent to seek refuge from the Threads in the natural caves of the northern mountain ranges. The significance of the southern hemisphere lost meaning in the immediate struggle to establish new settlements in the north. Recollections of Earth receded further from Pernese history with each successive generation until memory of their origins degenerated past legend or myth and into oblivion.

The original Fort constructed in the eastern face of the great West Mountain range soon grew too small to hold the colonists. Another settlement was started slightly to the north, by a great lake conveniently nestled near a cave-filled cliff. Ruatha Hold, too, became overcrowded in a few generations.

Since the Red Star rose in the East, it was decided to start a holding in the eastern mountains, provided suitable accommodations could be found. Suitable accommodations now meant caves, for only solid rock and metal (of which Pern was in distressingly light supply) were impervious to the burning score of Thread.

The winged, tailed, fiery-breathed dragons had now been bred to a size which required more space than the cliffside Holds could provide. The ancient cave-pocked cones of extinct volcanoes, one high above the first Fort, the other in the Benden mountains, proved to be adequate, needing only a few improvements to be made habitable. However, such projects took the last of the fuel for the great stonecutters (which had been programmed for only diffident mining operations, not wholesale cliff excavations), and subsequent holds and weyrs were hand-hewn.

The dragons and the riders in their high places and the people in their caves went about their separate tasks and each developed habits that became custom, which solidified into traditions as incontrovertible as law.

Then came an interval—of two hundred Turns of the planet Pern around its primary—when the Red Star was at the other end of its erratic orbit, a frozen, lonely captive. No Thread fell on Pern’s soil. The inhabitants began to enjoy life as they had thought to find it when they first landed on the lovely planet. They erased the depredations of Thread and grew crops, planted orchards, thought of reforestry for the slopes denuded by Thread. They could even forget that they had been in grave danger of extinction. Then the Threads returned for another orbit around the lush planet—fifty years of danger from the skies—and the Pernese again thanked their ancestors, now many generations removed, for providing the dragons who seared the dropping Thread mid-air with their fiery breath.