"Three: Since the 'Life-Service' of the tube contains a couple of hundred percent of safety factor, why shouldn't some of that safety factor be employed to get the ship back home--maybe ten hours at the most--thus saving a lot of money?" Steve began to see the beginnings of an attack on the Theory of Limits, against which there is only a dogmatic defence, ending in the reduction to an absurdity, and culminating in the posing of an unanswerable decision. It is sort of like the age-old argument as to where space begins and where being a planet ends. Being a-space does not begin when one leaves the planet; men flew through the air for centuries before they crossed the void to the other planets. Yet somewhere in the trip across interplanetary space, the first travellers must have traversed first the limit of Earth, passed into Space, and then entered the boundary of Venus. Where Earth ends and space begins is the Limit; and the easiest thing to attack is this Theory of Limits. Earth claims legally that the boundary of Her Domain begins at a height of five hundred miles above the surface. This is a dogmatic decision, adhered to because it has been agreed upon by all. So, legally, an orbiting Station at 499 miles is not in space; while legally the sister Station operating at 501 miles _is_ in Deep Space. Factually, each of these stations lie within two-tenths of one percent of being in, or out, of space; and since the surface of the Earth is far from being as smooth as a sheet of plate glass, the Limit is based upon Earth's somewhat arbitrary Sea Level. Similarly, if a tube's life is rated at ten thousand operating hours, and a safety factor is accepted at five hundred, can the tube be deemed inoperative at five hundred and ten hours? Especially when these 'over-age' tubes are returned to Earth or to whatever planet can use them and resold as 'Used' tubes to factories and installations where their failure will not cause a call-out of the Guardians. Many such 'Used' tubes, Steve knew, gave a total of twenty thousand hours of service. But Steve had his answer ready and waiting. "A few hours more or less isn't of vital importance," he said; "but what about the really weak jobs?" Wrightwood nodded. "That particular gentleman has been reprimanded. But since then you've grounded three of my ships with less than a total of twenty hours overtime." Steve shrugged. "Just so they wouldn't end up with five or six thousand hours on them--waiting for a lazy day on Earth to change them at leisure. Especially when the ship has been Earthing every week or so." "But why be more than normally hard? Why attack Interstellar harder than the rest?" "I don't; I have my orders and I'll see that they're carried out." "You can't think for yourself?" sneered Wrightwood. "I can and I do--and I think we're right." "You'll change--when you learn what they're doing to you," said Wrightwood. "What do you mean?"