It is a profoundly erroneous truism, repeated by all copy-books and by eminent people when they are making speeches, that we should cultivate the habit of thinking of what we are doing. The precise opposite is the case. Civilisation advances by extending the number of operations we can perform without thinking about them.

— Alfred North Whitehead in his [book: Introduction to Mathematics]

(which reminds me that Bertrand Russell’s [book: Principles of Mathematics], which predates his and Whitehead’s [book: Principia Mathematica] by 7 years or so, has been on my queue for a long while; anyone who’d like to read it along with me is hereby welcome to)