Comment by ndriscoll

The person I replied to said they know what monoid means, so they're familiar with algebra. The explanation is intuitive for someone familiar with undergraduate algebra (adapted to also assume some familiarity with programming and show how it connects). That's literally where the meme comes from, an intuitive remark from an introductory text on category theory. If you think it's impenetrable, it's not for you. You don't have the correct background, so ignore it.