I must have read Robert A. Heinlein's The Puppet Masters twenty or thirty times, easily, since the first time I read it in my mid-to-late teens. I can't say it's his best, but it's certainly one of the better works from what I consider to be his golden period. But in all those re-readings, I somehow failed to catch a rather huge logic hole in the plot - until realization suddenly burst in on me today.The Puppet Masters is, arguably, the classic mind-controlling-aliens-invade story (if anyone has another candidate to suggest, please do). The Titans control their hosts (human and otherwise) through physical contact, most often at the spine just below the neck. They reproduce extremely rapidly, and soon posses an extremely large percentage of the population - large enough that the protagonist, Sam, calls it a "saturation" point, and the Titans actually drop the masquerade.The goal of the Titans is to possess the entire human race - effectively, to spread themselves and their control to the uncontrolled portion of humanity. In North America, that uncontrolled population resides on the East and West coasts. They primarily advance this goal through infiltration, and also by using dogs and some other animals as carriers at night out of the Red (i.e. Titan-saturated) zone into the Green (free human) zone. The goal of the uncontrolled humans, on the other hand, is to resist takeover, to free the enslaved population, and to kill the Titans.Now here's the problem: early in the book, in chapter three, Heinlein introduces a drug called "tempus fugit". It's freely available in pill or injectable liquid. It increases subjective perception and reaction time by - well, Heinlein contradicts himself within the same paragraph:...I took them occasionally to make a twenty-four-hour leave seem like a week. ... Primarily, though, they just stretch your subjective time by a factor of ten or more - chop time into finer bits so that you live longer for the same amount of clock-and-calendar. Sure, I know the horrible example of the man who died of old age in a month through taking the pills steadily...Note that ten-to-one is given as the minimum alteration (despite Heinlein's earlier referral to an effective seven-to-one ratio). In chapter 21, Sam says "Suppose we have just twenty-four more hours; we could fine it down to a month, subjective time." Since he's proposing this to his new wife, this thirty-to-one dose is presumably not dangerous. Even higher subjective speeds are specified later, in chapter 24:The doctor gave me a short shot of tempus and I spent the time - subjective, about three days; objective, less than an hour - studying stereo tapes through an overspeed scanner.That is, at a minimum, a 72-to-1 increase in perceived time, and when he takes it, he's recuperating from serious burns. I'm afraid I've over-explained, but here's the basic point: why weren't the free humans dosed with tempus every time they invaded the infected zone? From the first time, when they were trying to get video proof of the titans' existence, to the last, when they went in to give antitoxin to the human population, tempus would have made their task about a thousand times easier. And yet they didn't use it, or even discuss using it. And what about the Titans? They have access to tempus too, but are never mentioned as using it at all. Which raises an interesting point: does tempus affect the Titan who is controlling a human, if the human takes it? If so, the Titans could have created high-speed assault & infection agents very easily. On the other hand, if the tempus does not affect Titans, then that raises a whole new interesting question. What happens when a human being controlled by a Titan is dosed with tempus? Suddenly they're thinking and reacting ten to 72 (or more) times faster than their master. Can the Titans exert meaningful control over their host under those conditions? If so, virtually unstoppable high-speed infectors seem to be an obvious option for them. And if not, why didn't the free humans send tempus-dosed troops to inject tempus into infected humans in zone Red?Yet another odd lapse in the story appears in chapter 24:What we needed was [...] something that would disable humans or render them unconscious without killing, and thereby permit us to rescue our compatriots. No such weapon was available, though the scientists were all busy on the problem. A "sleep" gas would have been perfect, but it is lucky that no such gas was known before the invasion, or the slugs could have used it against us.But when we go back to chapter 8, when the Titan-ridden Sam is recaptured much earlier in the story:With his other hand he thrust something against my side; I felt a prick, and then through me spread the warm tingle of a jolt of "Morpheus" taking hold. I made one more attempt to pull my gun free and sank forward.Okay, it's an injection rather than a gas. But it knocks out a highly trained agent before he can do anything about it. It's even called "Morpheus", for god's sake! Leaving out the absolutely obvious possibility (which absolutely nothing in the book rules out) of sending tempus-dosed troops with Morpheus injectors to knock out the population, Morpheus alone seems to be an invaluable weapon for either side. They're obviously both aware of the drug. And yet it is only used once, in the above passage.Perhaps I'm being unfair to Heinlein. But he himself described the care that he put into his work - I recall an anecdote he wrote about spending a week with his wife writing calculation after calculation on huge rolls of butcher paper, in order to derive a point about an orbit or trajectory that went into only one line in a novel. Two logic holes such as this in one of his golden age novels...well, that's just astonishing.Or perhaps this is one of those occasions where his editors overrode his wishes and forced him to self-censor? I've only read the original edition, so I can't be sure.Another minor point that occurred to me: To defend themselves from the Titans, the free humans adopt mandatory nudity. Several times, they mention a concern that the weather will soon be getting colder. Why wasn't transparent clothing ever considered?It's still a great read. Heinlein was, without question, a master storyteller. Which may explain why I never noticed these gaping logic holes before!