Textual editing is to literary and historical studies what mathematics is to physics and statistics is to the social sciences: it's a major part of the hardwiring that makes the whole enterprise work. It can also be incredibly unglamorous. You have to sit for a long time with old manuscripts, comparing them line by line, noting the discrepancies, and then use a formidable amount of brainpower to try to work out which version is most likely to be correct. In the Renaissance, these skills became important as we tried to figure out how to reconcile the different copies of Greek and Roman writing that had been made by monks through the long centuries since antiquity—many with wild differences, many hard to read, some with large holes in the middle.
English (like French, German, Czech, and Polish) is written in more or less the same alphabet used by the ancient Romans, albeit with a few tweaks: the Romans, for instance, had no letter J, nor W. But it could have been very different if the Emperor Claudius had had his way with the Latin language.