Mandala 10 closes the Rig Veda with its most varied and, in places, most philosophically ambitious material, standing apart from the ritual-focused family books in tone as much as in date. Its Purusha Sukta, hymn 10.90, describes a cosmic being, Purusha, sacrificed by the gods to create the universe, the sun from his eye, the wind from his breath, and, in verses of enormous later social consequence, the four varna classes of Hindu society from different parts of his body, a passage cited for millennia both to justify and, especially in the modern period, to sharply criticize the varna and caste system as later practiced. Its Nasadiya Sukta, hymn 10.129, the so-called Hymn of Creation, opens with radical uncertainty rather than confident cosmology, "there was neither non-existence nor existence then," and ends by openly doubting whether even the gods know how creation began, "who then knows, who here will declare it," among the most quoted expressions of philosophical humility in any ancient religious text.
The mandala also includes the Nadistuti Sukta, praising the rivers of the region by name and providing historians one of their most valuable sources for reconstructing early Vedic geography, alongside a wedding hymn, funeral hymns, and a memorable lament spoken by a compulsive dice player mourning his ruinous gambling addiction.