There also is the excellent book "Visual Differential Geometry and Forms" by Tristan Needham, which takes a similar visual intuitive explanation style. Also it features pictures of fruit pierced by lots of toothpicks.

I recently came across the existence of Penrose string diagram after curiously and naively researching the existence of index free notation for linear algebra. This seems to be a very interesting paper in the very same category of things I'd love to study and learn about but probably won't ever find the time!

This looks pretty good. Minor gripes: quite a few typos, and the pictures are often a couple pages away from the page that refers to them, making reading a bit inconvenient if your screen fits only one page. I only have a monochrome printer but I might spend a few bucks on a color printout at the local copy shop.

Now, that is a noteworthy weekend reading. Thank you!

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