There is a way around every tabu, knock on wood—but just watch out that the wood doesn't knock back! s it time?" Jarth Rolan asked anxiously. Pilot Lan Barda pushed him gently back into a seat. "No, but very soon. And be calm—you're jumpier than a human." "But we've waited so long—yes, a long time. And I am anxious to get home." Lan peered calmly out of his vehicle. They were hovering in Earth's upper atmosphere, at the permitted limit. "Be patient. These people have almost reached the critical