Hello, I am seeking the opinion of mathematicians. I want a solid understanding of pure mathematics. I would like your opinions on where to start. My background in formal mathematics courses ended with the standard calculus series. I pursued no further classes while attending college. My plan is to start from the very basics and build up my knowledge through what would be considered a solid master's level degree of proficiency in the discipline. My interests are mainly what would be considered "pure" math, but down the road I could see optimization and statistics being very interesting. I have no interest in mathematics as it applies to natural science. So, does anyone have any recommendations on where to begin laying the foundation? Please also note that I currently have a decent job and have no desire to go back to school. I am doing this purely as a hobby. I'd like to thank the community in advance for your suggestions and guidance.