The Vishnu Sukta 1.154 of Rigveda says that the first and second of Vishnu's strides (those encompassing the earth and air) are visible to the mortals and the third is the realm of the immortals. The Trivikrama describing hymns integrate salvific themes, stating Vishnu to symbolize that which is freedom and life. The Shatapatha Brahmana elaborates this theme of Vishnu, as his herculean effort and sacrifice to create and gain powers that help others, one who realizes and defeats the evil symbolized by the Asuras after they had usurped the three worlds, and thus Vishnu is the savior of the mortals and the immortals (Devas).