Understanding why Bayes' theorem is true isn't the hardest part. P(A and B) is both P(A) P(B|A) and P(B) P(A|B), and the result follows. I find this derivation

Understanding why Bayes' theorem is true isn't the hardest part. P(A and B) is both P(A) P(B|A) and P(B) P(A|B), and the result follows. I find this derivation easier to remember than the usual formula, by the way.