I've just read "The Music of the Primes" by Marcus du Sautoy, it is worth a read. I'm not from a maths background, but I'd like to develop a deeper understanding of the concepts. The poetry of math is something I'd like to experience and I feel like I didn't find as much joy in math as there is in the world of numbers.
Elliptical curve crypto-systems sounds like a direction I might want to head towards. I have no concept of where to start, or how in depth I would need to go to understand elliptical curves. Geometry was the most interesting math to me, but I am willing to move in different directions based on advice and materials.
In sum, I want to sit down with math again to give myself the chance at something I haven't experienced, the music of mathematics. There is no timeline or test on the horizon. What captivates you about math? What are the most interesting questions? Where would you recommend I start?
Thank you for any thoughts ahead of time.
A very nice book is Paul Nahim's "An imaginary tale: The story of $\sqrt{-1}$". The books by William Dunham ("When Euler met l'Hôpital", "Journey through Genius", and others) give a historical perspective.
Free for personal use are several nice textbooks by The Trillia Group.