This essay connects two of Humboldt's thoughts. First: to understand one another is, simultaneously, not to understand one another, to assent is at once to dissent. Indeed, no speaker gives a word the same meaning as understood by the listener. In the listener's reaction, we find the linguistic freedom to contradict what is being said to them, and the basic minimum comprehension that is necessary to understand one another is determined by the rules shared by all those who speak that same language. This process brings together rule and freedom: the rule derives from how the language influences the speaker, while the freedom derives from how the speakers influence the language. Second: it is not merely a question of understanding the world, as if the world were already established and one simply had to adjust to its reality. On the contrary, reality needs to be both established and understoood, yet without descending into mere subjectivity nor into a simple intersubjective convention. Humboldt retains that the two fundamental constituents of language sound and its sensoriality, concept and its spirituality require the mediation of a third element in which to meet: the mediating element is always of a sensory nature. Language shapes thought and expresses interior spiritual activity through the sound of speech, so that the sensory element sound and the spiritual element concept are thus united. Any intellectual activity would go unnoticed were it not for sound, which externalises it and thus allows it to be perceived through the senses. Thought finds clarity and concept is represented only when united with sound. Yet language can only develop in a social context: we can only understand ourselves when we can check with others whether what we think and say is understandable. Objectivity is enhanced if the word we speak is returned to us from someone else's mouth.