Focus on In Thee Rejoiceth (Poulakis) and analyze the Hymn.
Similar to Klontzas, the Poulakis painting was inspired by a hymn.  The Syrian monk John of Damascus composed the hymn and it was used in the Divine Liturgy of Saint Basil the Great during the Liturgy of the Faithful. The hymn is as follows:
Poulakis Klontzas John of Damascus