My last day at the the library of the Centro FGL in Granada...
It's not the first book on Lorca and music, because there are several others, though of much more limited scope. It's not the definitive book, either, because it leaves things out. I would say it is the first more or less complete attempt to lay out the territory. Someone else could come along and do it more completely, or even better.
I like saying that it is a medium sized book on a vast subject.
So it is with scholarship. You are rarely the first to do something: you are almost always joining an ongoing discussion. If you are the last, that means that nobody else will even discuss what you have done. You want your work to inspire others, not be a dead end. You want to write something substantial (not too short) but at the same time not [necessarily] exhaustive.
A lot of detail is good, but if the reader feels you are tellings them everything you found, without any selectivity, then the risk is a certain triviality. "Trivial" details are meaningful to me, as researcher, as a way of getting at the granularity of the subject matter, but a profusion of them in the text produces a sensation of excess, as though. The iceberg theory says that you should not reveal everything you know. Your writing has depth through a process of omission.