The quotation in the title is attributed to Frank Adams and appears in several places:
- In the preface of [2002, Operads in algebra, topology and physics]: "to operate the machine, it is not necessary to raise the bonnet (look under the hood)."
- In [Stasheff, 2004, What is ... an operad?]: "to operate the machine, it is not necessary to raise the bonnet (look under the hood)."
- In footnote 4 of [Riehl, 2011, Algebraic model structures]: "to operate the machine, it is not necessary to raise the bonnet."
However, I have trouble finding any earlier appearances of the quote. I found something in that spirit in [Adams, 1978, Infinite loop spaces, §2.3]:
Unfortunately, as I have hinted in §2.1, the construction and use of machines takes work. Therefore this chapter will be written as an essay in machine appreciation; it is not intended to qualify the reader for a mechanic's certificate.
Question. Does the quotation in the title appear in the writings of Frank Adams? Or was it a spoken remark that has been transmitted through folklore?
(I apologise for the non-mathematical question, but I thought MathOverflow would be the most likely place to find the answer.)