It has been understood for millennia that what makes humans unique above all creatures is our power of speech, that is to say, our ability to communicate. We certainly have the capacity for the most rudimentary forms of communication: “food,” “water,” “hungry,” “danger.” But we also have a unique capacity to speak of immaterial realities: “love,” “spirit,” “god,” “heaven.” In the preceding and most recent centuries, some have taken great pains to explain how alike we are to certain animal species. But one glorious and irrefutable example suffices to emphasize our uniqueness: we can communicate about things we cannot see, and about those things that are not strictly necessary for material survival. Monastics who never procreate can speak of the sublimities of divine love. Yeoman farmers who will never study Kant or Descartes may nonetheless speak of existential angst; which speech does nothing to plant or harvest the crops.
Indeed, it is particularly the most obvious inutility of certain aspects of human speech that make us most unique and make us most human. But perhaps such inutility is only obvious from a certain perspective. For the power of articulation is precisely the ability to grasp the abstract realities from concrete particulars. The observations of dozens of planting seasons yields the deduction of planetary motion. That is to say, the uniquely human power of speech is the necessary comprehension of the realities underlying the perceived world.