A programming language is a system of notation for describing computations. A useful programming language must therefore be suited for both description(i.e., for human writers and readers of programs) and for computation (i.e., for efficient implementation on computers). But human beings and computers are so different that it is difficult to find notational devices that are well suited to the capabilities of both.
- R. Tennant - Principles of Programming Languages, Prentice Hall, 1981