TITLE: Read old articles instead books.
QUESTION [14 upvotes]: I'd like to know if there is a site, or maybe a collection of books, where I can read old articles in mathematics in order to study topics directly from the source, instead reading books in the field. I always feel that my study is incomplete when I don't know the motivation, or the history backgrounds, of the definitions or theorems (even when I read good and classical books).

REPLY [3 votes]: I haven't browsed their collection in detail, but Numdam has a lot of good stuff.