Ask HN: Do you recall any book or course that made a topic finally click?

Ask HN: Do you recall any book or course that made a topic finally click?
454 by curious16 | 319 comments
Sometimes it takes a book or a course (or explanation from a mentor) for a topic to finally click for you that you were struggling with for a long time. For me, it was Stanford's EE261 course that made Fourier Transform click for me. Here is the link: https://ift.tt/03JF5oA Similarly for deep learning it was fast.ai courses. For programming it was How to Design Programs at www.htdp.org. Your topic of choice may be anything, not necessarily CS.