At an All-night Vigil for a Sunday, the Typicon calls for lessons to be read seven times, and at a festal vigil, six: at the end of Vespers, at Matins after the first and second kathismata, follwing the polyeleos, following the third and sixth odes of the canon, and at the end of Matins (the latter only on Sunday). The purpose of these readings is exhortation and instruction, while at the same time they serve for the refreshment of the memory and the relaxation of the body, since they are listened to while sitting. The first reading is an excerpt from the Holy Scriptures (from the book of the Acts of the Apostles or from the Apostolic epistles); the next four readings are taken from patristic commentaries concerning the excerpt which was read; the sixth is taken from the lives of the saints; and the seventh, a moral-ascetical "catecheses," is taken from the writings of Ven. Theodore the Studite.
——《Liturgics》Archbishop Averky
This is great, do you have a source for this quote?