Bliss found especially useful their "triangle of reference": the physical thing or "referent" that we perceive would be represented at the right vertex; the meaning that we know by experience (our implicit definition of the thing), at the top vertex; and the physical word that we speak or symbol we write, at the left vertex. The reversed process would happen when we read or listen to words: from the words, we recall meanings, related to referents which may be real things or unreal "fictions". Bliss was particularly concerned with political propaganda, whose discourses would tend to contain words that correspond to unreal or ambiguous referents.[citation needed]