The story of Guile is the story of bringing the development experience of Emacs to the mass of programs on a GNU system.
Emacs, when it was first created in its GNU form in 1984, was a new take on the problem of “how to make a program”. The Emacs thesis is that it is delightful to create composite programs based on an orthogonal kernel written in a low-level language together with a powerful, high-level extension language.
Extension languages foster extensible programs, programs which adapt readily to different users and to changing times. Proof of this can be seen in Emacs’ current and continued existence, spanning more than a quarter-century.
Besides providing for modification of a program by others, extension languages are good for intension as well. Programs built in “the Emacs way” are pleasurable and easy for their authors to flesh out with the features that they need.
After the Emacs experience was appreciated more widely, a number of hackers started to consider how to spread this experience to the rest of the GNU system. It was clear that the easiest way to Emacsify a program would be to embed a shared language implementation into it.