David Spivak and other folks at Azimuth Forum[0] have been great at providing high quality discussions on ideas in this course and others. Many thanks.
[0]https://www.azimuthproject.org/azimuth/show/John+Baez [1]https://forum.azimuthproject.org/discussion/1717/welcome-to-... [2]http://math.mit.edu/~dspivak/teaching/sp18/7Sketches.pdf