I'm currently documenting sources from Julian the Apostate for a paper later this semester, and I'm wondering if anyone can help me out here. I'm looking for a way to determine how Julian's satirical work "Symposium" from 361 AD survived.
In case people don't know what I'm talking about: it's also known as "the Caesars". You can find a translation by simply googling that.
All I know is that many other works critical of Christianity around this time survived through commentaries by later Christian authors, but I can't find a reliable source (i.e. anything other than Wikipedia).
How to do this:
Step 1. Find out where this text exists in a critical edition. In this case the book you're after is:
C. Lacombrade, L'empereur Julien. Oeuvres complètes, vol. 2.2. Paris: Les Belles Lettres, 1964: 32-71.
Step 2. Locate this in a library. It happens to be in my library, so I might be able to grab it for you later if you can't access it yourself.
Step 3. Critical editions generally have a discussion of the manuscripts. You want to find out what manuscripts we have, where they are from, and when they are dated to. That gives you a 'earliest known starting point'. It doesn't explain how they survived from Antiquity, but it does tell you how we still have a text.
Step 4. You can extrapolate a little from step 3, depending on the type and quantity of manuscripts available.
Step 5. References in other works. Assuming you become reasonably conversant with Julian's Caesares, if you read the secondary literature on it and find out which ancient authors interact with it, if any, this also helps construct a picture of how the text survived.
Sorry I can't answer your question directly, but I will try and follow up step 2 for you.