H.M. Edwards in the preface to his book on the Riemann Zeta Function, summarises his philosophy on learning Mathematics:
...I have tried to say to students of mathematics that they should read the classics and beware of secondary sources
In trying to learn more, I feel that I have accumulated a bookshelf full of secondary sources which I have left largely unread. So I would like to take heed of Edwards's advice and read some classics for the wonderment of it and for the respect I would gain for mathematicians of the past. I would like to exercise creativity over rigour, at least for a little while.
But this begs the question: what are the classics? And this is what I hoped to ask about.
Which primary sources do you feel are suitable for self-study? Naturally this is a broad question, but people must have their favourites, and I am hoping for some recommendations on the basis of these personal preferences.