The Joy of X: A Guided Tour of Mathematics, from One to Infinity

by Steven H. Strogatz

maths always involves both invention and discovery: we invent the concepts but discover their consequences.

The eminent linguistic philosopher J. L. Austin of Oxford once gave a lecture in which he asserted that there are many languages in which a double negative makes a positive but none in which a double positive makes a negative — to which the Columbia philosopher Sidney Morgenbesser, sitting in the audience, sarcastically replied, “Yeah, yeah.”)

Some imaginary friends you never outgrow.

Iota that.