As you've probably been told time and time again, Latin was one of Modern English's ancestors. Many words, idioms, and constructions come into our language from Latin, some of which are really unexpected nuggets of similarity. A favorite example of mine is in book 4 of the Aeneid, wherein Mercury in tenuem ex oculis evanuit auram — "he vanished from the eyes, into thin air" (emphasis mine).
What I'm going to show you here is a trick you can use either in translating Latin or understanding the implications of derived English words. It's technically called the "inchoative infix." The inchoative infix turns up in verbs with an internal "sc" right before the personal endings of the first principle part of the verb (the first person present active indicative conjugation) — such as obsolesco, to be forgotten; evanesco, to vanish (whence "evanuit" in the previous paragraph); nosco, to become familiar with.
The "sc" gives the word the implication of a situation that has come into being over time, or is now beginning. So obsolescence implies not only that something is out of use, but that it was once in use, and has become less so. It's the same with the other examples I gave: the word implies a transition between circumstances.
In fact, you can, under some situations, give a past tense translation of a present tense "sc" verb: bene haec verba nosco can be translated as "I recognize these words well," but it is perfectly acceptable, and sometimes more accurate to render the phrase as "I have come to know these words well." Try it yourself. Find an "sc" word and try to see how an "I have come to" or "I am beginning to" restatement works.
According to Wikipedia, this pattern comes from a similar infix in classical Greek, which was "σκ" and not "sc." And of course, in addition to English, the "sc" pattern has remnants in living Romance languages.
What's the lesson in this? I can suggest several.
- Latin is fun!
- Language evolves, and complexities that were once apparent can become a matter of subtle implication.
- Cum omnia discas, cum nulla dissuescas.
My thanks to Oolong and Excalibre, who helped me touch up some mistakes in the first version of this writeup. | 
