The Character of Physical Law
Richard Feynman's The Character of Physical Law is a collection of seven transcripts from a lecture series bearing the same name. It's essentially a philosophy of science piece, except seen from a scientist's point of view rather than a philosopher's. Thus, the ﬁrst lecture sets the stage by defining and explaining a running example: The law of gravitation. Throughout the rest of the series, this law serves as a model for a brilliant explanation of laws of nature: How they come into being, what they mean, what they don't mean and how they frequently lead to the discovery of other laws. He also explains how a single law can be understood in several different framings, and that even if they say exactly the same thing, they can sometimes lead to radically different further discoveries (with examples given from his own work in quantum mechanics).
Feynman was famous (some would say infamous) for taking an informal approach to science; he'd often prefer visualizations to equations when he could get away with it. He had a huge aversion to "stuffiness" (which is also why he enjoyed poking fun at philosophers). While he freely acknowledges how useful (and necessary) mathematics is to theoretical physics, he often managed to explain himself with the precise necessary minimum of mathematical formalism. This lecture series is no exception; while there are a number of formulae (reproduced in copied handwritten form in the book; no doubt based on use of blackboard in the original lectures), they're only introduced when they're useful — rather than dazzle the audience with a litany of Greek letters, Feynman resorts to math when he either needs the reasoning tools or the information density, otherwise preferring plain English. He had a gift for that; explaining ﬁendishly complicated concepts in down-to-earth terms without ever seeming condescending (or playing fast and loose with facts). He had a knack for cutting away all unnecessary complications. He believed (and ends the book with stating it outright) that the beauty of nature was due to its simplicity, that complex phenomena ultimately grew from simple concepts — and this view evidently carried through to his teaching style.
As an educator, I wish I had his ability to make hard subjects easy.
Another thing that clearly comes across is how physics (and, by extension, life in general) was essentially a game to him. He delighted in ﬁguring out how bits and pieces of the universe worked and ﬁt together, and that delight is evident in his explanations.
Recommended, and I should read some more Feynman.