Guillaume was introduced to linguistics by the comparative grammarian Antoine Meillet, a student of Ferdinand de Saussure.
The challenge this poses for a linguist is to find the means of analyzing the preconscious mental operations, the "psychomechanisms" as he called them, giving rise to each part of speech.
These, along with various research notes and essays, make up some 60,000 manuscript pages kept in the Fonds Gustave Guillaume at Laval University in Quebec City.
The only volume of Guillaume's writings translated into English is Foundations for a Science of Language, a series of excerpts from various lectures and essays, the first of which, from his inaugural lecture of 1952–1953, begins as follows: "Science is founded on the insight that the world of appearances tells of hidden things, things which appearances reflect but do not resemble.
This observation is not mine – it comes from the great Meillet, who wrote that 'a language involves a system where everything fits together and has a wonderfully rigorous design.'