I’ve often had this experience: certain technical topics look extremely difficult to break into. No matter how many standard resources and popular content that you read through, every one of them seems to speak a foreign language. I’ve felt this while studying topics like complex numbers, Fourier’s transform, relativity, to name a few.
I am of the opinion that either I’m too dumb or writers of many popular expositions on such topics have not understood it clearly. And I secretly like to think later is the case. The authors never seem to be running into some questions that immediately come to mind while studying: for example, asking why are we doing this? But then there are some resources that are godsend. The author runs into exact same questions that I mentioned above and, gasps, tries to answer them.
Tristan Needham’s work Visual Complex Analysis falls into such group. In about 65 pages of chapter 1, he explains complex numbers in a beautiful and simple language. He also sets out to give you big picture view. For example, he gives a quick tour of geometry via group theory lens and even talks about quaternions.
I simply have lot of respect for such authors. They just decide that some topic can be explained in a plain language and few pictures. And then they also make the hard work to pull it off. Simply beautiful stuff!