". . . those continual prayers that are performed with the body, out of which prayer in the heart is born. . . ."

St. Isaac the Syrian, "Concerning aspects of the way of stillness," =chap. 1 of the long-lost Second Part of the Writings, trans. Sebastian Brock. Sebastian Brock, "St Isaac the Syrian: two unpublished texts," Sobornost 19, no. 1 (1997): 16 (7-32).  Context:  "an easy rule that is useful for someone who is weak":  "because the feeble body grows weary of standing continually on its feet in order to fulfil the customary acts of worship, and for this reason is often hindered from those continual prayers that are performed with the body, out of which prayer is born, you should fall down many times on your face at your seat—just as is described by your hands—and spend a while in supplication, in such a way that converse with scripture may be intermingled with prayer.  Then, the light which you will receive from these two quarters will be raised up, to your soul's enjoyment.  As a result prayer will give you delight because of reading, and you will again be illumined in reading by means of the keys of prayer."