This is a friendly Lambda Calculus Introduction by Dustin Mulcahey. LISP has its syntactic roots in a formal system called the lambda calculus. After a brief discussion of formal systems and logic in general, Dustin will dive in to the lambda calculus and make enough constructions to convince you that it really is capable of expressing anything that is "computable". Dustin then talks about the simply typed lambda calculus and the Curry-Howard-Lambek correspondence, which asserts that programs and mathematical proofs are "the same thing". This talk was recorded at the Lisp NYC meetup at Meetup HQ.