I'm wondering if it's advantageous to read the original works of Gauss, Jacobi, Cauchy and others (in particular, Jacobi).
Many people say that it's worth it to read original (not translated) works of literature - you have the author's own diction and get a better feel of his/her cogitation. I wonder if it's the same way for mathematics textbooks - is it worth it to study some Latin and etc., and struggle through strange notation, to read the masters?
Apologies if such a question has been asked already, I didn't find it here.
If you're looking to understand the concepts well, rather than get some historical background, I would actually advise against this. More modern treatments will use up to date language, tie theories in with newer concepts that the original authors didn't know about, and have the exposition guided by understanding the ideas in a wider context.
I even find that for research topics barely a decade old, a survey article written a few years later is often better to learn from than the first paper - by knowing some of the results that follow, the survey article authors can phrase the definitions and exposition in a way that makes them seem natural, in a way that the original authors couldn't.
That's not to say there aren't good reasons to read these older works of course, but I find it's much more helpful to have a reasonable understanding of the wider theory first.