The Lenten Triodion is the service book of the Orthodox Church that provides the texts for the divine services for the pre-Lenten weeks of preparation, Great Lent, and Holy Week. It is called the triodion because the canons appointed for Orthros during this period are composed of three odes each. The weeks of preparation, and especially the Sunday gospel readings, serve to exercise the mind, whereas the fasting of Great Lent focuses on the body, and Holy Week's services exercise the spirit.