Programs Are Written for People to Read, and Only Incidentally for Machines to Execute
Knuth's 'literate programming' concept: programs are not merely functional instruction sequences but literary works explaining ideas to human readers. Good programs should be as readable as good essays; code and documentation are inseparable. This belief drove him to explain every algorithm in narrative form in TAOCP.
Source: Literate Programming, Donald Knuth, The Computer Journal, 1984 / Selected Papers on Computer Science, Donald Knuth, CSLI Publications, 1996