Some form of the hymn known as the Sanctus has been a near-universal feature of Christian eucharistic prayers, or anaphoras, since late antiquity. The hymn often consists of two elements. The first, the Sanctus proper, is based on Isa 6:3 (see Rev 4:8). The second, which is known as the Benedictus, is usually based on Matt 21:9. In the Roman Canon, for example, these two elements are found in the following form: