zbinga
Learning Lagrangian mechanics when all your life you only ever heard about the Newtonian approach is a lot like stumbling upon Scheme after years of programming in C.
I'm looking forward to cracking the cover of SICM once more this summer!
For what it's worth, the pirated version I had (back in the old days) had your name on it (plus a crack group's name and probably BBS phone number). I remember thinking "Hey, that's the Apple Writer guy, what else did he write?" and that's how I found GraFORTH. Bought Leo Brodie's book and had a blast learning the language, then actually implementing small Forth-like languages for the fun of it. There was a Byte book, "Threaded Interpretive Languages" that gave me several epiphanies about programming in general and language design in particular.
I used Apple Writer for years, until eventually my typing speed increased so much that the program couldn't keep up with me anymore when typing long paragraphs (the word wrap algorithm, that was run after each character, apparently took time proportional to the length of the current paragraph, with a big enough constant that my 1 MHz Apple II started dropping keystrokes regularly despite the program having a 32-character buffer). I eventually resorted to disabling word-wrap while typing, and re-enabling it prior to printing (Control-Z, I think it was). Later, I bought a Zip Chip that increased the computer speed to about 3.5 MHz, and the problem disappeared.
I wasn't using Apple Writer by then, because I had discovered another word processor, a weird, Rube Goldberg contraption called Gutenberg Sr. that used double-high-resolution graphics at a time when few programs did, and had a more powerful markup language (troff-inspired, I found out later), could two two-column printing and had some page layout capabilities, and had great support for printer-downloadable fonts, including user-defined ones. The interface was atrocious but the software itself was powerful.
But if you cannot relate an exercise to the subject matter you just studied, it might also be the case that you think you understand what you just read, but don't really do. It's easy to read math superficially, honestly believing that one has understood the point, when in fact the "mental image" the authors wished to impart on you has not been grasped.
So you should not ignore the exercises, but work hard at them. They (well, some of them) are supposed to be hard. They are supposed to make you think, not just rehash what you just read. And after all that hard work, hopefully, something will click and you will be ready for the next section.
And then you will feel awesome.
In the TeX source code, you can put as many spaces you want between words and sentences, TeX does not mind and will produce the exact same result.
So in the context of TeX documents, "One space is correct and nothing else" is either meaningless or false.
I know about the cloud. I distrust the cloud. The cloud is not for me.