You need to understand how human beings bring together their brains and enable their ideas to combine and recombine, to meet and, indeed, to mate. In other words, you need to understand how ideas have sex.

Ridley frames innovation as a fundamentally combinatorial process: new ideas arise when existing ones are brought into contact, mixed, and recombined. By likening this to sex, he emphasizes that creativity is not usually a solitary act of “genius” but a social, networked phenomenon—dependent on exchange, communication, and the freedom to connect minds. The metaphor also implies variation and selection: recombination generates many possibilities, and environments (markets, institutions, cultures) determine which combinations persist. The quote’s significance lies in its challenge to romantic individualism about invention, pointing instead to collaboration, trade, and open societies as engines of progress.