In Vaishnavism and Shaivism, God, Vishnu or Shiva respectively, is personified as male. God, however, transcends gender in these sub-schools, and the male form is used as an icon to help focus the Puja (worship). The use of icons is not restricted to male forms. It takes various forms and shapes. The Shaivites and Vaishnavites worship God in non-anthropomorphic, symbolic male-female images as well, such as the linga-yoni and Saligram respectively. In their literature, the principle of God's true nature as sexless is emphasized as in the Vishnu sahasranama.