One of the major problems encountered in time travel is not that of accidentally becoming your own father or mother. There is no problem involved in becoming your own father or mother that a broad-minded and well-adjusted family can’t cope with. There is no problem about changing the course of history—the course of history does not change because it all fits together like a jigsaw. All the important changes have happened before the things they were supposed to change and it all sorts itself out in the end.
The major problem is quite simply one of grammar, and the main work to consult in this matter is Dr. Dan Streetmentioner’s Time Traveler’s Handbook of 1001 Tense Formations. It will tell you, for instance, how to describe something that was about to happen to you in the past before you avoided it by time-jumping forward two days in order to avoid it. The event will be described differently according to whether you are talking about it from the standpoint of your own natural time, from a time in the further future, or a time in the further past and is further complicated by the possibility of conducting conversations while you are actually traveling from one time to another with the intention of becoming your own mother or father.
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The Restaurant at the End of the Universe is one of the most extraordinary ventures in the entire history of catering.
It is built on the fragmented remains of an eventually ruined planet which is (wioll haven be) enclosed in a vast time bubble and projected forward in time to the precise moment of the End of the Universe.
This is, many would say, impossible.
In it, guests take (willan on-take) their places at table and eat (willan on-eat) sumptuous meals while watching (willing watchen) the whole of creation explode around them.
This, many would say, is equally impossible.
You can arrive (mayan arrivan on-when) for any sitting you like without prior (late fore-when) reservation because you can book retrospectively, as it were, when you return to your own time (you can have on-book haventa forewhen presooning returningwenta retrohome).
This is, many would now insist, absolutely impossible.
At the Restaurant you can meet and dine with (mayan meetan con with dinan on when) a fascinating cross-section of the entire population of space and time.
This, it can be explained patiently, is also impossible.
You can visit it as many times as you like (mayan on-visit reonvisiting … and so on — for further tense correction consult Dr. Street-mentioner’s book) and be sure of never meeting yourself, because of the embarrassment this usually causes.
This, even if the rest were true, which it isn’t, is patently impossible, say the doubters.
Quote from The Restaurant at the End of the Universe, by Douglas Adams.