And now let's get back to the OP. Consider the physical and mental process of copying a manuscript. You look to your left where you have the document. You read a sentence and try to remember it. You turn to the right, where your blank paper (papyrus or whatever) is and write. You have to retain what you saw on the document accurately enough to write the whole thing down. This takes great concentration.
Now consider this. The original has sentences both before and after the one you are copying. You not only have to remember your sentence, but remember where it is in the document. Because of this, tehe acts concerning the original are quite a bit more difficult than the act of writing in the copy. It is therefore quite easy, believe me, to let your mind skip a word, phrase or even a sentence.
On the other hand, adding a word or phrase is usually deliberate: a scribal correction to what he thinks is the right text, for example. On this line, considering the history of the Antiochan (Byzantine) church as compared to the Alexandrian church (with such weirdos as Origen), I believe the bibliology of the church at Antioch to be much superior, resulting in a corresponding reverence for the text. Thus the scribes at Antioch were more careful, producing a more accurate text, the Byzantine. (Just consider all the corrections in the margin of Vaticanus.)
Now consider this. The original has sentences both before and after the one you are copying. You not only have to remember your sentence, but remember where it is in the document. Because of this, tehe acts concerning the original are quite a bit more difficult than the act of writing in the copy. It is therefore quite easy, believe me, to let your mind skip a word, phrase or even a sentence.
On the other hand, adding a word or phrase is usually deliberate: a scribal correction to what he thinks is the right text, for example. On this line, considering the history of the Antiochan (Byzantine) church as compared to the Alexandrian church (with such weirdos as Origen), I believe the bibliology of the church at Antioch to be much superior, resulting in a corresponding reverence for the text. Thus the scribes at Antioch were more careful, producing a more accurate text, the Byzantine. (Just consider all the corrections in the margin of Vaticanus.)