 Humboldt’s notion of articulation first introduced in his “On Thinking and Speaking” of 1795 formed the theoretical basis also for his empirical work into the phonemic structures of natural languages where his research anticipated modern linguists’, e.g., Trubetzkoy’s and Jakobson’s, conception of phonology. Already in 1795 he drew a clear distinction between the physical sound of nature on the one hand and the “articulated” sounds that constitute language on the other. In his empirical studies he discovered that the latter alone would form a clearly discernible “unit” (scharf zu vernehmende Einheit), capable of embodying features to allow these sounds to enter into specific relationships with each other and any other sound (GS Vol 7: 67). What this means is that for Humboldt, the individual sound of a given language can be formed only “in relation to the others” (in Beziehung auf die übrigen) that make up the entire “sound system” (Lautsystem) of that language (GS Vol 7: 67). He thought it possible and desirable to set up schemata accounting for the different classes of phonemes (Buchstabenlaute) found in the world’s languages, and the different relationships into which these may enter according to their affinities (Verwandtschaft) or their mutual opposition (“in Verschiedenheit einander gegenüberstellen” GS Vol 7: 69). In working with over a dozen native South and Central American languages, Humboldt created one such schema enabling him to describe and to compare the phonetic systems of these different  languages.[4] 